I would find it funny と I would think that it's fun はどう違いますか？
説明が難しい場合は、例文を教えて下さい。

I would find it funny- This means that you'd be amused at something, and you would probably laugh at it. Like a joke or a comedy movie.
I would think that it's fun (Which works better as "I think that it would be fun") - This means that you would enjoy yourself, and would have a good time doing an activity. Like a game.