Well,The Tamagotchi Version 4's are very different than the Version 3's. It has different games. and The names of the games are "Jumping Rope", "Mimic", "Shape", "Dance" and "Flag". (There is only 5 games, but you get another game when you go to work. You go to work by going to the connection icon and clicking work. You also do this when you go to school. So when you go to work it's like playing another game.)
The version 4's also has a post icon instead of a light icon. (The light automatically turns off when it falls asleep.) In the post icon, you can recieve, but not send, mail. You can recieve important mail, the option with the explanation point, you can recieve presents, a robber and other stuff in the regular option, the option that lookds like a regular letter, and mail that will tell you how you are doing, the option with the star on the envlope.
And on a version 4 you recieve "skill points" from different things your Tamagotchi does. (Such as play a certain game and go to school...) Those "skill points" will affect what job your Tamagotchi gets.
The food isn't much different from the version 3 though. But in the snacks section instead of an apple there is an orange, but that's it.
And another difference is that on a version 4 you can make your "gotchi points" go up to 99,999, instead of 9,999!
Hope I Helped,
Pupsluv24
P.S. Feel free to PM me to ask questions.