C and CF lenses are the older lenses that don't have the outer latest body design.

The CB, CFI and CFE lenses have the latest body design and are all the same except for a slight differences:
CB - has a cheaper shutter mechanism, no 'F' setting, no electronic contacts - discontinued
CFI - has newer shutter, has 'F' setting, no electronic contacts
CFE - has newer shutter, has 'F' setting and has electronic contacts

Art.