Is Request Coalescing just another name of back pressure?

I am wondering if request coalescing and back pressure are the same thing? Or is request coalescing just an implementation of back pressure ?

To me both means "if there is too much requests, well do not send them all at once".

Hum, after a second thought: Maybe back pressure means: "client delays the requests a little bit, but do send all of them" and request coalescing means: "clients don't send twice the same request in a time window and cache the results of the request" ?