running start vs racing start

running start and racing start both are nouns.

Word	Noun	Adjective	Verb	Adverb
running start	Yes	No	No	No
racing start	Yes	No	No	No

As nouns, racing start is a hypernym of running start; that is, racing start is a word with a broader meaning than running start:

running start: a racing start in which the contestants are already in full motion when they pass the starting line
racing start: the start of a race

running start (noun)	racing start (noun)
a quick and auspicious beginning	the start of a race
a racing start in which the contestants are already in full motion when they pass the starting line