Most of the difference between GET and POST has been already discussed in there respective section. It all depends upon requirement when you want to choose GET and POST and knowledge of these differences help you to make that decision.
1) GET method passes request parameter in URL String while POST method passes request parameter in request body.
2) GET request can only pass limited amount of data while POST method can pass large amount of data to server.
3) GET request can be bookmarked and cached unlike POST requests.
4) GET is mostly used for view purpose (e.g. SQL SELECT) while POST is mainly use for update purpose (e.g. SQL INSERT or UPDATE).