If I add a user to sudoers to be able to perform root functions, does it mean this user is the same as root?
No, Sudoers is controls who can run what commands as what
users on what machines and can also control special things such as whether you need a password for particular commands.
You can give all command privileges to user, or just give some privileges to run particular command, like :
#allow all command to user with sudo iamsudo ALL=(ALL) ALL
#only allow reboot command to user with sudo iamsudo ALL=/usr/sbin/reboot
Hope this will help.