there are only the two sizes. the one you find on your ipod or computer is the most common. the larger size is being phased out. with nicer headphones you usually get an adapter for both.
wasn't sure if you wanted the exact name/size:
Full size =1/4 inch or
mini plug =1/8 inch (3.5mm)
These are just for music players. If you're getting an old mixer, it can be different.