When creating a new user, I see this below box. What are the different between them?
uid is unix user id and if you do not specify, the system will generate one for you. User name actually is called full name, which is not used in login. Therefore only the login is required.
The actual Esx or esxi server stores data like so
Here the first field is login, the third is uid, and the 5th is the user name.