“Standard users” are your everyday users. This user class is distinguished by its inability to make system-wide changes (for example, software installation).
“Guest accounts” have access to the computer, but not to any resources on that computer (unless such access is explicitly permitted). Generally used in kiosks or shared machines. Generally considered dangerous.
“Service accounts” are non-human users. Generally highly restricted. “Managed” service accounts are managed by the system itself and thus don’t require explicit passwords or other user setup.
“Shared accounts” are shared between users. Breaks non-repudiation, and generally is a bad idea. Should be avoided whenever possible.
Account Management - Password Policies
Complexity & length (everything from simple character set & length rules to more complicated measures of entropy)
History (a.k.a., reuse)
Maximum password age (a.k.a., expiration)
Minimum password age (how long a user must wait before they can change their password again; used in conjunction with password history to force users to actually use different passwords)
Account Management - Account Policies
This is more Windows-specific. In particular, account policies in Active Directory apply to all objects in the directory (users, computers, etc.)
An account policy is generally a set of pre-applied configuration parameters that the user (or computer, or whatever) cannot change. However, in Active Directory you can also set some access policies, which determines under what conditions we have access to a particular system or object (RBACs/ABACs/CACs as we discussed above), through the same “User Properties” interface.