Hello, @Bhunesh r.
AppMon Agent specifically designed for a particular technology and/or application layer whereas a single OneAgent per host is required to collect all relevant monitoring data of supported technologies.
There are also many other advantages Dynatrace OneAgent has. Have a look at the below links for more insight.
https://www.dynatrace.com/support/doc/appmon/application-monitoring/agents/
https://www.dynatrace.com/support/help/setup-and-configuration/dynatrace-oneagent/
Regards,
Babar
I like this link as a summary of what you get with Dynatrace. A few things overlap with AppMon but the majority is unique to Dynatrace.
https://www.dynatrace.com/support/help/get-started/introduction-to-dynatrace/