I came across a nifty article explaining the difference between the legacy Log Analytics Agent and Azure Monitor Agent.

There's some feature improvements in terms of what logs can be retrieved with AMA but I think the biggest notable difference is performance-related. As per Microsoft: "The Azure Monitor agent provides a throughput that is 25% better than legacy Log Analytics agents. Migrate to the new AMA connectors to get higher performance, especially if you are using your servers as log forwarders for Windows security events or forwarded events"