It is not a jump that cancels a move, allowing a transfer into other techniques without waiting for a recovery to finish. These phenomena are both called “jump cancel” by many, even involving the same mechanics, but they are two different techniques.
For example, Fate/Unlimited Codes does not normally allow for a super cancel, but by appending a jump () to the end of a special move’s command input, it becomes possible to create combos that go from special moves into special moves, and from special moves into super special moves (it is thought that the jump cancel’s motion is canceled by the special move).
This technique may also allow a normally-uncancelable normal move to segue into a special move if the system allows this, making it an indispensable skill to have.
This technique is possible in Street Fighter III, valid in a few cases. In particular, it is believed that the reason that the standing double circle command is possible is because the system is allowing for the possibility of a high jump; if done in time, the high jump is cancelled without the character (Hugo) ever leaving the ground despite the input direction having been upwards twice, and the move (Gigas Breaker) goes off on the ground.