As adjectives the difference between conventional and stubborn
is that
conventional is pertaining to a convention, as in following generally accepted principles, methods and behaviour while
stubborn is refusing to move or to change one's opinion; obstinate; firmly resisting.
As a noun 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.