"might" includes much uncertainty. "may" , the opposite. So the two sentences are the similar meanings. But the first one is more uncertain than the second one.

May is present tense, so strictly speaking it implies a 'possibility now' whereas might implies 'perhaps will ...' but really they are used as interchangeable. might is past tense, and should be used in preference to may in cases of a past event that turned out impossible - 'if he hadn't been caught cheating he might have become Olympic champion'