Trolls and Elves have long ears, inhuman strength, better eye sight and hearing, and fangs, the elves lost their tusks, but if you look at their mouths their canines are quite pronounced. Showing their troll ancestry just hides behind their lips.
What elves gained was more digits in their hands and feet, what they lost in pure muscle mass they gained greater dexterity though trolls are fairly fast as well. Elves and trolls can quickly evolve depending on what they are exposed to. So, elves and trolls are among the most adaptable races on Azeroth.