helping hand vs assist

helping hand and assist both are nouns.

Word	Noun	Adjective	Verb	Adverb
helping hand	Yes	No	No	No
assist	Yes	No	Yes	No

As nouns, assist is a hypernym of helping hand; that is, assist is a word with a broader meaning than helping hand:

helping hand: physical assistance
assist: the activity of contributing to the fulfillment of a need or furtherance of an effort or purpose

Other hypernyms of helping hand include aid, assistance, help.

helping hand (noun)	assist (noun)
physical assistance	(sports) the act of enabling another player to make a good play
	the activity of contributing to the fulfillment of a need or furtherance of an effort or purpose

helping hand (verb)	assist (verb)
	act as an assistant in a subordinate or supportive function
	work for, or be a servant to
	give help or assistance; be of service