transmission vs posting

transmission and posting both are nouns.

Word	Noun	Adjective	Verb	Adverb
transmission	Yes	No	No	No
posting	Yes	No	No	No

As nouns, posting is a hyponym of transmission; that is, posting is a word with a more specific, narrower meaning than transmission:

transmission: the act of sending a message; causing a message to be transmitted
posting: the transmission of a letter

Other hyponyms of transmission include forwarding, mailing, telephotography.

transmission (noun)	posting (noun)
the act of sending a message; causing a message to be transmitted	the transmission of a letter
the gears that transmit power from an automobile engine via the driveshaft to the live axle	a sign posted in a public place as an advertisement
communication by means of transmitted signals	(bookkeeping) a listing on the company's records
an incident in which an infectious disease is transmitted
the fraction of radiant energy that passes through a substance