"Hey, just wanna clarify here! I said the Sims 3 was like playing with Clay, not the Sims 4, because you're using the same base face and simply tweaking certain aspects of the 3D model. In the Sims 4, you're actively swapping out parts of the 3D model. TS3 is like molding a clay nose onto a face, TS4 is like chopping off the clay if you don't like it in favor of another clay nose that you then mold."
Just chiming in to respond to the above quote from Jayed. :)
In my opinion, I felt like making sims in 4 was more like molding clay. It's all personal perspective I guess. I also think every in-game screen shot I see from sims 4 makes the sims look identical, face structure wise. It is a fact, though, that you can swap out individual features in sims 3. I do this all the time. There's individual eyes, noses, and mouths to choose, and there is not just one base face to choose from, there are several. Happy Simming ;)