table mat vs hot pad

table mat and hot pad both are nouns.

Word	Noun	Adjective	Verb	Adverb
table mat	Yes	No	No	No
hot pad	Yes	No	No	No

As nouns, table mat and hot pad are synonyms defined as:

table mat and hot pad: a pad for use under a hot dish to protect a table

table mat (noun)	hot pad (noun)
a pad for use under a hot dish to protect a table	heater consisting of electrical heating elements contained in a flexible pad
	a pad for use under a hot dish to protect a table