Allows you send an event from one event sheet to one or more event sheets.
"Call Function" and "On Function" are just different words for "Send Event" and "On Sent".
Both Plugins:
"Call"/"Send" an Event with multiple Parameters.
Can have multiple "On Function"/"On Sent" Conditions in different/same Event Sheets.
(I may be overlooking something, but i just cannot see the difference other than the words)
Looking at the documentation for the Function plugin, it describes it and shows examples of using like a function in a traditional programming language like what I am used to. Usually you have one "On" block that gets executed (shared code). It appears though that you are correct you can use multiple "On" blocks and have them all fire on one "call". I wasn't aware that could be done.