forwarding vs transmittal

forwarding and transmittal both are nouns.

Word	Noun	Adjective	Verb	Adverb
forwarding	Yes	No	No	No
transmittal	Yes	No	No	No

As nouns, transmittal is a hypernym of forwarding; that is, transmittal is a word with a broader meaning than forwarding:

forwarding: the act of sending on to another destination
transmittal: the act of sending a message; causing a message to be transmitted

Other hypernyms of forwarding include transmission, transmitting.

forwarding (noun)	transmittal (noun)
the act of sending on to another destination	the act of sending a message; causing a message to be transmitted
the advancement of some enterprise