Hi!

Locking a user prevents the user from logging in, but the SystemUser node is not in a special mode in the system, so it will still be returned in queries and so on. So for example, if you have a Employee content class, and you lock one of the employees, the employee will not be able to login, but it will still be listed in the employee page.

Deactivating a user means that the user is excluded from all regular queries (where you don't specify that you want to include deactivated content). This means that in the example above, a deactivated employee will not be able to login (the query to see if a user is matching the specified credentials will not return a match), and the employee will not be listed in the employee page.