Server monitoring means tools and approaches used for auditing the application performance as well as that of web servers. Basically, it refers to gathering machine- and infrastructure-level metrics like memory usage, Disk I/O, CPU utilization, and throughput. Though these metrics are helpful in monitoring the health of their infrastructure, they fail to identify and troubleshoot issues with respect to application code.
Unlike server monitoring, application monitoring understands Business Transactions. This makes it easy to prioritize performance bottlenecks on the basis of their criticality and the transactions that they affect.
Server monitoring software lacks code-level insight into performance bottlenecks. But AppDynamics provides class and method-level detail about performance bottlenecks, which helps to identify and solve problems.
Many server monitoring tools have alerting abilities, but in its case, the static alerts are set either too high or too low. This leads to either few or too many alerts but all alerts tend to be inaccurate. In the case of AppDynamics, you get alerts from algorithms that measure deviation from normal behavior so that you get accurate alerts.