Female tiger barbs are a little deeper in the body and noticeably wider when viewed from above. Males when in good condition have much brighter colours, in particular, they develop a strong red colouration from the nose up over the head towards the dorsal fin.
They are not the easiest of barbs to breed. In good water conditions you can get them to spawn readily enough, but the eggs won't hatch in anything but soft acidic water. The fry are also small and very sensitive to nitrogen pollution, (as indeed, are the adults).
Green tiger barbs are the same species so the same applies, although the colouration is more difficult to spot on very dark examples.