a standard User Account and an Administrator Account.
Since there is no need to re-create well documented facts read the following then go to the link it came from for additional information.
"The primary difference between a standard user and an administrator in Windows Vista is the level of access the user has over core, protected areas of the computer. Administrators can change system state, turn off the firewall, configure security policy, install a service or a driver that affects every user on the computer, and install software for the entire computer. Standard users cannot perform these tasks and can only install per-user software."
In terms of security, is the Admin user account in Vista similar to the Standard user account? From what I can see, the main difference is that to get permissions in the Admin account, you just click a button. Whereas in the Standard account you have to enter in the admin password. But both Admin and Standard accounts seems to pop up the same warnings. Let me know if there's some big difference in security between the two. Or if they're fairly similar. I'm currently using a Vista Admin account and it looks like switching everything to a Standard account would be a big job.