A quicj question on .service in Linux

We have two locations where .service files scripts are stored. What is the signifiance of these two locations? Thanks

/usr/lib/systemd/system
/etc/systemd/system

@sam007 ,

usr/lib/systemd/system : This is where all files of units that have been preinstalled system-wide by services are located. /etc/systemd/system : All files of system-wide units that are created or edited by users are located here.

If there are unit files under /etc/systemd/system with the same name as under usr/lib/systemd/system , preference is given to those from /etc systemd/system , i.e they are loaded by the system.