true slime mold vs slime mould

true slime mold and slime mould both are nouns.

Word	Noun	Adjective	Verb	Adverb
true slime mold	Yes	No	No	No
slime mould	Yes	No	No	No

As nouns, slime mould is a hypernym of true slime mold; that is, slime mould is a word with a broader meaning than true slime mold:

true slime mold: a slime mold of the class Myxomycetes
slime mould: a naked mass of protoplasm having characteristics of both plants and animals; sometimes classified as protoctists

Other hypernyms of true slime mold include slime mold.

true slime mold (noun)	slime mould (noun)
a slime mold of the class Myxomycetes	a naked mass of protoplasm having characteristics of both plants and animals; sometimes classified as protoctists