They are not the same, Regedit is a program for managing windows registry. Windows Registry is a hierarchical database that stores configuration settings and options on Microsoft Windows operating systems
Gpedit.msc is a program to manage Windows group policies. Group Policy provides the centralized management and configuration of operating systems, applications, and users' settings in an Active Directory environment.
You can read more about windows group policy here https://en.wikipedia.org/wiki/Group_Policy
and read more about windows registry here https://en.wikipedia.org/wiki/Windows_Registry