How does CurrentControlSet differ from ControlSet001 and ControlSet002?

Solution 1:

Yes, you only need to update the CurrentControlSet key...

ControlSet001 and ControlSet002 are alternating backups of CurrentControlSet, you don't need to update them.

Edit: As K noted, CurrentControlSet is an alternating symbolic link to either ControlSet001 or ControlSet002. The other key is kept as a backup for the Load Last Known Good Configuration boot option.

Edit 2: See Microsoft KB Article 100010: What are Control Sets? What is CurrentControlSet?
Original page link broken, see archive.org backup page instead.

Solution 2:

CurrentControlSet is technically not a "backup" as Gordon states.
It is a symbolic link to one of the ControlSets on the computer. It always points to the ControlSet that is currently loaded.