No , this is not the same, see each plugin you have on your vcsa create sessions , each running thread in side creates a session with your vcenter , even if it is not doing anything, it periodically do the garbage collection and thus create connections, each login, each operation all creates sessions. There is a way to increase the number of sessions,( I dont recall how though)
What i did was i turned off unused plugins, and disabled unwanted services on vCSA
and increased number of sessions. as said i dont recall how to do it .
it was either in vpxd.conf --> vclient.maxConnectionCount>100</maxConnectionCount // this is to increase number of concurrent connections to vCenter
Webclient.properties in vsphere-client directory on vCSA // This limits number of Web Client sessions
or combination of those