What's the difference between GET and POST AJAX requests?

I've always done GET requests regardless, but I think I should probably look into it :P .

The first question is if GET can be used for passwords. I know that it's generally considered best practice to use POST for password forms, but isn't this a bit different? Or am I wrong?

Also, are GET requests more readily cached than regular HTTP requests? I know that POST requests are not cached whatsoever, but I've had no problems (thus far) with AJAX-GETs and caching.

In GET, the parameters are send in URL, whereas in POST there is nothing like that.
I'd also doubt about it bt actually there is not much difference b/w these.