yes there are two standards. the 3.5" are the one like mine. they were first in old amigas I think and early PCs and were the standard till the end. before that there were this huge 5.25" floppy disks which are known in germany just as floppies (the 3.5" are just known as diskettes)
the bigger ones are thinner and way more bendable
edit:
5.25"
