Originally having been developed from Judo, and while still recognizable as closely related and even as a style of Judo, there are some differences from modern Olympic Judo. For example BJJ encourages free sparring without striking (also known as "rolling"), against a live, resisting opponent very similar to Randori in judo, however the rules related to this sparring have key differences.
Divergence from Kodokan rules
Since judo was introduced to Brazil there have been changes in the rules of sport judo—some to enhance it as a spectator sport, and some for improved safety. Several of these rule changes have greatly de-emphasised the groundwork aspects of judo, and others have reduced the range of joint locks allowed and when they can be applied. Many of the banned techniques are preserved in the judo kata, and are practised to varying extents in different clubs. Brazilian Jiu-Jitsu did not follow many of these changes to judo rules, and this divergence has given it a distinct identity as a martial art, while still being recognizable as a sub-style of judo. Other factors that have contributed towards the stylistic divergence of BJJ from sport judo include the Gracies' desire to create a national martial art, the influence of Brazilian culture, and the Gracies' emphasis on full-contact fighting.
BJJ permits all the techniques that judo allows to take the fight to the ground, these include judo's scoring throws as well as judo's non-scoring techniques that it refers to as 'skillful takedowns' (such as the flying armbar). BJJ also allows any and all takedowns from wrestling, sambo, or any other grappling art. BJJ also differs from judo in that it also allows a competitor to drag his opponent to the ground, and also even to drop to the ground himself provided he has first taken a grip. Early Kodokan judo not only allowed all that BJJ now allows, it even allowed a fighter to drop straight to the ground without first taking a grip.
BJJ's different rules set and point scoring mechanisms are designed to give BJJ an arguably more practical emphasis, by rewarding positions of control from which the grappler could strike their opponent (if it weren't for the sport's restrictions against striking).
Ground fighting
BJJ is most strongly differentiated by its greater emphasis on groundwork, in contrast with judo's greater emphasis on throws, due to both its radically different point-scoring system, and the absence of most of the judo rules that cause the competitors to have to recommence in a standing position. This has led to greater time dedicated to training on the ground, resulting in enhancement of judo's groundwork techniques by BJJ practitioners.
There are also many techniques that are allegedly created by BJJ, though they already existed in Kodokan judo. This misconception is often the result of incorrect assumptions by BJJ practitioners who simply assume that the techniques they learned in BJJ classes originated there. It is also due in some instances to BJJ practitioners genuinely rediscovering techniques that they did not know existed in judo, such as the Gogoplata. However some new techniques have certainly been developed by BJJ practitioners, such as the inverted omoplata or "rubber guard" defensive hold.
Along with BJJ's great strengths on the ground comes its relative weakness with standing techniques such as striking. Many Judo practitioners also regard the art as having greatly lost the ability to execute effective throws and takedowns, a cornerstone of the original Judo. A similar, but contrary opinion is held by BJJ practictioners of the ground technique in Judo, which is regarded as having become extremely limited and of decreased effectivenes. There is an increasing amount of cross-training between the sports of BJJ and Judo, and striking based arts such as Muay Thai.
The Gi
The Brazilian Jiu-Jitsu practitioner's uniform is similar to a judogi, but often with tighter cuffs on the pants and jacket. This allows the practitioner to benefit from a closer fit, providing less material for an opponent to manipulate, although there is a significant overlap in the standards that allows for a carefully selected Gi to be legal for competition in both styles. To be promoted in Brazilian Jiu-Jitsu, the wearing of the Gi while training is a requirement.
As is the case with judo, the term kimono is sometimes used to describe the outfit, especially in Brazil.
Divergence from Kodokan rules
Since judo was introduced to Brazil there have been changes in the rules of sport judo—some to enhance it as a spectator sport, and some for improved safety. Several of these rule changes have greatly de-emphasised the groundwork aspects of judo, and others have reduced the range of joint locks allowed and when they can be applied. Many of the banned techniques are preserved in the judo kata, and are practised to varying extents in different clubs. Brazilian Jiu-Jitsu did not follow many of these changes to judo rules, and this divergence has given it a distinct identity as a martial art, while still being recognizable as a sub-style of judo. Other factors that have contributed towards the stylistic divergence of BJJ from sport judo include the Gracies' desire to create a national martial art, the influence of Brazilian culture, and the Gracies' emphasis on full-contact fighting.
BJJ permits all the techniques that judo allows to take the fight to the ground, these include judo's scoring throws as well as judo's non-scoring techniques that it refers to as 'skillful takedowns' (such as the flying armbar). BJJ also allows any and all takedowns from wrestling, sambo, or any other grappling art. BJJ also differs from judo in that it also allows a competitor to drag his opponent to the ground, and also even to drop to the ground himself provided he has first taken a grip. Early Kodokan judo not only allowed all that BJJ now allows, it even allowed a fighter to drop straight to the ground without first taking a grip.
BJJ's different rules set and point scoring mechanisms are designed to give BJJ an arguably more practical emphasis, by rewarding positions of control from which the grappler could strike their opponent (if it weren't for the sport's restrictions against striking).
Ground fighting
BJJ is most strongly differentiated by its greater emphasis on groundwork, in contrast with judo's greater emphasis on throws, due to both its radically different point-scoring system, and the absence of most of the judo rules that cause the competitors to have to recommence in a standing position. This has led to greater time dedicated to training on the ground, resulting in enhancement of judo's groundwork techniques by BJJ practitioners.
There are also many techniques that are allegedly created by BJJ, though they already existed in Kodokan judo. This misconception is often the result of incorrect assumptions by BJJ practitioners who simply assume that the techniques they learned in BJJ classes originated there. It is also due in some instances to BJJ practitioners genuinely rediscovering techniques that they did not know existed in judo, such as the Gogoplata. However some new techniques have certainly been developed by BJJ practitioners, such as the inverted omoplata or "rubber guard" defensive hold.
Along with BJJ's great strengths on the ground comes its relative weakness with standing techniques such as striking. Many Judo practitioners also regard the art as having greatly lost the ability to execute effective throws and takedowns, a cornerstone of the original Judo. A similar, but contrary opinion is held by BJJ practictioners of the ground technique in Judo, which is regarded as having become extremely limited and of decreased effectivenes. There is an increasing amount of cross-training between the sports of BJJ and Judo, and striking based arts such as Muay Thai.
The Gi
The Brazilian Jiu-Jitsu practitioner's uniform is similar to a judogi, but often with tighter cuffs on the pants and jacket. This allows the practitioner to benefit from a closer fit, providing less material for an opponent to manipulate, although there is a significant overlap in the standards that allows for a carefully selected Gi to be legal for competition in both styles. To be promoted in Brazilian Jiu-Jitsu, the wearing of the Gi while training is a requirement.
As is the case with judo, the term kimono is sometimes used to describe the outfit, especially in Brazil.
