shipment vs payload

shipment and payload both are nouns.

Word	Noun	Adjective	Verb	Adverb
shipment	Yes	No	No	No
payload	Yes	No	No	No

As nouns, shipment and payload are synonyms defined as:

Other synonyms of shipment include cargo, consignment, freight, lading, load, loading.

shipment (noun)	payload (noun)
the act of sending off something	goods carried by a large vehicle
goods carried by a large vehicle	the front part of a guided missile or rocket or torpedo that carries the nuclear or explosive charge or the chemical or biological agents