rubbish heap vs junk pile

rubbish heap and junk pile both are nouns.

Word	Noun	Adjective	Verb	Adverb
rubbish heap	Yes	No	No	No
junk pile	Yes	No	No	No

As nouns, rubbish heap and junk pile are synonyms defined as:

rubbish heap and junk pile: an accumulation of refuse and discarded matter

Other synonyms of rubbish heap include garbage heap, junk heap, refuse heap, scrapheap, trash heap, trash pile.

rubbish heap (noun)	junk pile (noun)
an accumulation of refuse and discarded matter	an accumulation of refuse and discarded matter