No difference really, they both mean the same thing and can be used interchangeably :)

They're interchangeable. They're close synonyms.

There's one difference I can think of. There's one way you can use <em>try</em> but not <em>attempt</em>.

<em>Try</em> can be an intransitive verb meaning "generally, to make an effort." <em>Attempt</em> can't be used this way. <em>Attempt</em> always refers to some specific goal. You can say:

"She may not always succeed, but she always tries."

If you wanted to use the word <em>attempt</em>, you could <em>not</em> say:

"She may not always succeed, but she always attempts."

You would have to reword it:

"She may not always succeed, but she always makes an attempt."

As with many pairs of synonyms in English, there's a very slight difference in "register." <em>Try</em> is the plain, simple, everyday word. <em>Attempt</em> is a little bit more formal. While you are learning, I suggest that you understand both words, but just use the word "try."

"Try" can be used about anything, trivial or important. "Attempt" carries a slight feeling of something grand or significant.

"I tried to open the bedroom window, but it was stuck."

"In 1922, a British expedition attempted to climb Mount Everest, but failed to reach the summit."

You <em>could</em> say "attempted to open the bedroom window" in the first sentence but it would sound a little self-important. However, you can say or write "a British expedition tried to climb Mount Everest" and it sounds fine.