you may try google them on google picture. then you can see what they really are. They look differently.

李=李子，梅=梅子 To understand them, the best way is to search the pictures of 李子 and 梅子 on the "http://image.baidu.com/", then you will find they are different things. 李子 is Prunus L. and 梅子 is Armeniaca Mill. They are different species.

李 1.surname 2.plum 梅 1.surname 2.plum 3.flower of the prune tree In southern China there are more 梅子. In northern China there are more 李子. Most of 梅子are more sour , so we often use them to make processed foods. Most of 李子are sour and sweet , so we often eat them directly.

李 meant fruit of plum in China。 梅 meant the flower of plum at most time。