baby sitting vs tending

baby sitting and tending both are nouns.

Word	Noun	Adjective	Verb	Adverb
baby sitting	Yes	No	No	No
tending	Yes	Yes	No	No

As nouns, tending is a hypernym of baby sitting; that is, tending is a word with a broader meaning than baby sitting:

baby sitting: the work of a baby sitter; caring for children when their parents are not home
tending: the work of providing treatment for or attending to someone or something

Other hypernyms of baby sitting include aid, attention, care.

baby sitting (noun)	tending (noun)
the work of a baby sitter; caring for children when their parents are not home	the work of providing treatment for or attending to someone or something

baby sitting (adjective)	tending (adjective)
	(usually followed by `to') naturally disposed toward