reorder vs purchase order

reorder and purchase order both are nouns.

Word	Noun	Adjective	Verb	Adverb
reorder	Yes	No	Yes	No
purchase order	Yes	No	No	No

As nouns, purchase order is a hypernym of reorder; that is, purchase order is a word with a broader meaning than reorder:

reorder: a repeated order for the same merchandise
purchase order: a commercial document used to request someone to supply something in return for payment and providing specifications and quantities

Other hypernyms of reorder include order.

reorder (noun)	purchase order (noun)
a repeated order for the same merchandise	a commercial document used to request someone to supply something in return for payment and providing specifications and quantities

reorder (verb)	purchase order (verb)
assign a new order to
make a new request to be supplied with