I used Canons for many years !
they are broken down into 3 main groups:
single digit units are the PRO models [EOS1, 3, 5] alloy bodies, metal lens mounts
Double digit units are the PRO/Amateur models [EOS30 etc] alloy or plastic bodies, metal lens mounts
Triple and quad digit units are the consumer models [EOS300, 1000 etc] plastic bodies, plastic lens mounts
I have had a lot in the past - EOS1, 3, 5, 30, 300, 650, 1000 . . .
Here is some extra reading >
http://www.mir.com.my/rb/photography/hardwares/classics/eos/index.htm