Trickster is a character in a story, which exhibits a great degree of intellect or secret knowledge, and uses it to play tricks or otherwise disobey normal rules and conventional behaviour. Trickster often is fun character, as well as clown is. What is difference between clown and trickster? Where is border when trickster stop to be trickster and become clown? For example, Jar Jar Binks? Is he clown, or trickster?
I'm sort of combining my answer to this question with a comment based on your other question. I would agree with other comments that clowns are simply comic performers and there is no teaching aspect to what they are doing.
A trickster, mythologically speaking, is also a teacher, but in the sense that you are taught a lesson painfully. Often though, it's the only way the lesson comes through. The main aspect of a trickster is the trick aspects (may involve making the object of the trick look stupid, etc.) The trick is the most obvious aspect, to the point where many people aren't aware that there is a lesson being taught. Check Coyote in Native American stories.
Elsewhere, you asked about Yoda. I do not see him as a trickster because his teaching is what is most obvious and manifest. He may use trickster type actions as a tool, but that is secondary to his persona as a master teacher.
Let's find out.
Clown: 1. a comic performer, as in a circus, theatrical production, or the like, who wears an outlandish costume and makeup and entertains by pantomiming common situations or actions in exaggerated or ridiculous fashion, by juggling or tumbling, etc.
Trickster: 1. a deceiver; cheat; fraud.
There are more definitions for both, but I won't duplicate them here. Check 'em out.