What is the difference between changing a user's password and resetting it?

Answer 1

When you change passwords nothing else changes. If you reset, it means that everything is to be set to its default. For instance, if you have created particular set of rules/permissions for users and you change their passwords, rules will not be changed. But you reset all those users, you will have create all rules/permission from a scratch.

Answer 2

Forcing a password reset doesn't need you to enter a new password yourself. Instead, whenever the user logs on using his old password, said user will be prompted to change the password and will be unable to do anything else before having done so. This is a good way to force the user to change a password without having to give them the new one (without even having to know the new one). However, it gives the user freedom as to what to select as the new password.

Changing the user's password manually will allow us to enforce certain password rules (which, by the way, can be enforced by other means), but it also requires from us to deliver this new password to the user, as (s)he will be unable to log-in. Also, if the user has had any data encrypted using the current working password, force-changing it will render said encrypted data unaccessible.