Yes. As PSU version for OMS we have 188.8.131.52.10, whilst the agent is 184.108.40.206.7
This is because some PSU are OMS patch only.
How to Determine the List of Patch Set Update(PSU) Applied to the Enterprise Manager OMS and Agent Oracle Homes? (Doc ID 1358092.1)
Oracle Recommended Patches (PSU) for Enterprise Manager Base Platform (All Releases) (Doc ID 822485.1)
220.127.116.11.10 Enterprise Manager Base Platform Patch Set Update (PSU) (Doc ID 1575007.1)
18.104.22.168.7 Enterprise Manager Base Platform Patch Set Update (PSU) (Doc ID 1446550.1)
Typically if there is a hard pre-req it's listed in the readme for each patch, so be sure to check them out. Best Practice -- Apply latest OMS PSU, then apply latest Agent PSUs. The Agents can often have agent-side fixes that are tied to an OMS fix, so I wouldn't recommend to have a lower OMS level.