Difference between "fun" and "interesting"

In Japanese, there is no difference in definition between fun and interesting in their adjective forms. I know that fun also has a noun and verb form in English, but I am wondering is there any difference between "fun" (adjective definition) and "interesting"?

In all honesty, they appear to mean the same thing. Is there a time when you can replace one word with the other to have a completely different meaning?

EDIT: To explain myself a little bit more, interesting is defined as attracting your attention in Merriam Webster. When can something be fun and not attract your attention? In this sense, I feel as if fun encompasses interesting.

Solution 1:

The basic difference between the two is emotions it appeals to.

Fun is enjoyable. It causes pleasure - especially in active forms, as thrill, exhilaration, challenge, elation.

Interesting appeals to curiosity - learning, it's about things we want to know, see, learn, examine. Whatever reasons - be it for pleasure, or e.g. for professional interest or satisfying anxiety.

Since usually satisfying curiosity is pleasurable, these two are often correlated, but not always. A gruesome sight, say, bowels sticking out of a live person's ruptured abdomen, may be interesting, but definitely not fun. A secret document on enemy military movements will be interesting too, but definitely not fun. The pilot of a damaged airplane will definitely find the damage report interesting and absolutely not fun.

On the other hand, if you solved a hundred crosswords, solving one more may still be fun, but hardly interesting. Riding down a slide in entertainment park will be described as fun too - it may be interesting the first time, but then you're not curious about it any more, you just do it for fun. Being given unexpected presents is fun - but since you didn't expect them, you didn't have time to find that interesting.

Solution 2:

I read this question, and because I was curious I Googled: "interesting fun in Japanese". In one of the results I read a Japanese speaker making similar observations:

The adjective おもしろい/Omoshiroi has basically two meanings. One is 'interesting', another one is 'funny', they are used in various situations. [...] so sometimes I confuse fun, interesting and funny in English.

In case I should say 'interesting', I say 'funny':(

I found that information interesting because I am unfamiliar with the Japanese language, and it seemed odd that two adjectives which are so distinct in my mother tongue; funny and interesting, could be largely interchangeable in a different language. It didn't strike me as being funny as I didn't laugh, nor did I smile.

For example, interesting facts are pieces of information that provoke ideas or discussion that otherwise might not have occurred. Fun, or funny facts on the other hand, are amusing pieces of information which cause hilarity, laughter and generally speaking, make you smile.

Often you can have facts that are interesting which stimulate witty comments and reflections, the BBC programme QI is a fine example. Click on any word in the info cloud and discover for yourself.