There are hunters you can interact with[spoiler ] you could buy and sell items. they were carrying something from hunting like an animal hide. i cant remember at the moment. but they only had 8 gold. so you could not sell anything of decent value to them. Mercanaries, but i dont know what is capable with them. more variety in detail. I saw more than 4 types of potion bottles. they vary in shape, size, and color. more variety in armor. It was less frequent to see the same armor twice., except for guards/soldiers but thats expected. so yeah there are more armor types. i think there were more weapons, i just didnt pay that close of attention to that lol.

The voices are more varied. Each character seems more you unique because you dont hear the same voice over and over. If I had to guess, i would say every 125 to 175 characters in oblivion shared the same voice actor(except for unique one-of-a-kind characters). But for skyrim, i would guess every 25 to 50 characters share the same voice actor (except for unique characters again. I didnt do the exact math, but i figure im in range of whats correct. i dont remember how many unique NPC's are in oblivion, but 1400 comes to mind, or 2000 something lol.