In general the SEV has a cast aluminum cooling fan and an aluminum plate
mounted on the outside back of the alternator with one or two big diodes in
it hooked up in reverse. (The plate is "hot".)
The Bosch has a stamped steel cooling fan and the diodes are usually in a
pressed steel plate sort of recessed into the back of the alternator. The
Bosch also has 6mm end bolts holding it together while the SEV has something
like 10/32 screws (similar metric size) holding it together, in other words
smaller and daintier.
Many of the regulators used on either one can be adjusted for higher output
by increasing the spring tension. (Mechanical regs only, solid state need not
apply!)
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George Downs Bartlesville, Heart of the USA!