pool vs mud puddle

pool and mud puddle both are nouns.

Word	Noun	Adjective	Verb	Adverb
pool	Yes	No	Yes	No
mud puddle	Yes	No	No	No

As nouns, mud puddle is a hyponym of pool; that is, mud puddle is a word with a more specific, narrower meaning than pool:

Other hyponyms of pool include billabong.

pool (noun)	mud puddle (noun)
any of various games played on a pool table having 6 pockets	a puddle of mud
an excavation that is (usually) filled with water
an association of companies for some definite purpose
an organization of people or resources that can be shared
something resembling a pool of liquid
a small lake
a small body of standing water (rainwater) or other liquid
any communal combination of funds
the combined stakes of the betters

pool (verb)	mud puddle (verb)
join or form a pool of people
combine into a common fund