With borrowing from this answer:
service is an "high-level" command used for start, restart, stop and status
services in different Unixes and Linuxes. Depending on the
"lower-level" service manager, service redirects on different
binaries.
For example, on CentOS 7 it redirects to systemctl, while on CentOS 6
it directly called the relative /etc/init.d script. On the other
hand, in older Ubuntu releases it redirects to upstart.
service is adequate for basic service management, while directly
calling systemctl give greater control options.
Moreover, systemctl runs services file from this path: /lib/systemd/