Given the difference in the rules of sport jiu jitsu and sport judo, a number of techniques have developed that are used widely in one community and not at all in the other, even when they are legal (and effective) in both sports. Since I have a foot in both camps, I wanted to mention a few such techniques I’m aware of:
Sankaku-Jime Turtle Turnover
In judo, the turtle position is an effective way to escape ground work, because both people are stood back up on their feet if no progress is made on the ground. In that way, the turtle position is effectively used by many judoka to stall any kind of progress. Because of this a large number of techniques have been developed in judo to open up or to turnover the an opponent in a turtle position. One of the most popular is the sankaku-jime (triangle choke) turnover that is shown at the 2:10 mark of the following video:
PS: Thanks to my buddy Caleb for making the observation how few jiu jitsu people use this technique.
Kesa Gatama Pin
This is one of the most popular pins in judo and is often the first pin taught to a white belt judoka. However, it also happens to break one of the “commandments” of bjj. You are exposing your back by turning without having an underhook on the far side. I personally don’t like this technique in both sports, but that’s because my heart is not in it. If you’re committed to it, I’ve seen competitors in both sports (and also MMA) use it effectively.
Many jiu jitsu folks know how to do the clock choke but it’s very often far down on the list of attacks to try on a turtled opponent. Usually the first thought is “take the back with one or two hooks in”, then try for a gi choke such as the bow-and-arrow. On the contrary, for many judoka the first thought when face with a turtle opponent is “clock choke”. This may have to do with the fact that time is limited, and taking the back can often take some time. Also, a failed throw will often lead naturally into a choke given that one of your hands may already be gripping your opponents lapel.