Answer:
the difference between conservative and conventional is that conservative is a person who favors maintenance of the status quo or reversion to some earlier status while conventional is (finance) a conventional gilt-edged security, a kind of bond paying the holder a fixed cash payment (or coupon) every six months until maturity, at which point the holder receives the final payment and the return of the principal.
As adjectives the difference between conservative and conventional is that conservative is tending to resist change or innovation while conventional is pertaining to a convention, as in following generally accepted principles, methods and behavior.