Do you spar full contact in Aikido like in Judo? If not how do you spar? And what are some differences between the two?

Since Aikido is not really considered a "combative" art, and we don't have an Aikido forum, I'm moving this to General in hopes of your getting a better response.

It's called Randori.

It depends upon the style of aikido. Tomiki and Shodokan have tanto-randori, where one has a tanto (knife) and the other is unarmed. The former scores by stabbing/slashing their opponent, the latter by throwing/pinning/locking/disarming their opponent. I'm not sure if they have any set method for sparring with both practicioners unarmed.

 

Most forms of aikido that I know of, however, don't spar. Most work is done via paired kata, with one person delivering an attack and the other defending with a lock or throw, etc. There is jiyuwaza, however, where one or more attackers go after someone who tries to throw them and move about the mat in the most economical fashion, pretty much, trying not to get hit or taken down. Jiyuwaza for most styles only arises, from what I know, during the later kyu grades and onwards from there, though.

 

As for differences with judo - well, judo involves some groundwork, whereas most aikido don't, the aim being not to get taken down in the first place. Other than that, and judo's focus on randori, there are a few throws/locks in judo that are similar to some in aikido, no doubt thanks to Kenji Tomiki's influence. Aikido's sometimes referred to as 'judo at a distance'.