symbol? and string?

Aside from the issue of uninterned symbols, why are these separate and not the exact same thing?  Alternatively, are these any situations in which you need to differentiate between strings and symbols?

>>6
suppose you're in a system where strings don't exist separately and all you have is symbols. then:
(define op 'faggot)
(string-append 'Op\ is\  op) ; => Op is faggot
(string-append 'Op\ is\  'op) ; => Op is op

IHBT.