"It's funny" vs "It's fun"
Is there any difference between them?

Question

Answer

When your friend makes you laugh, you can say she/he is funny. We use funny who makes you laugh.

However, fun means an experience or activity that is very enjoyable and exciting. 
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Answer

A very noticeable difference, I think.

Fun = enjoyable

Funny = comical

Answer

They have different meanings.

Fun = 好玩 (ie. good play)
Funny = 滑稽 (ie. hilarious)

In addition, 'fun' can be both a noun and an adjective. 'Funny' is an adjective, and its noun form is 'funniness'.