Check out this article by SimsVIP!
1- There will be right-handed Sims… ¡but there will also be left-handed Sims!
2- The Sims 4 will work better in low-end machines than The Sims 3.
3- With the passage of time, hair and beard will grow.
4- The wind will make the Sims’ hair and clothing move.
5- With the Create a Sim feature, you will be able to change the feet size.
6- Pregnant Sims will have unique emotions that no one else will experience.
7- There will be three voice types for men and women.
8- There won’t be Wishes, but little goals for Sims to accomplish and gain awesome rewards.
9- Every life cycle will have a special emotion only for Sims in it.
10- Sims won’t die randomly anymore, like by a meteor strike or a lightning. They will die only by things done by the player.