showtime vs threshold

showtime and threshold both are nouns.

Word	Noun	Adjective	Verb	Adverb
showtime	Yes	No	No	No
threshold	Yes	No	No	No

As nouns, threshold is a hyponym of showtime; that is, threshold is a word with a more specific, narrower meaning than showtime:

Other hyponyms of showtime include birth, incipience, incipiency, starting point, terminus a quo.

showtime (noun)	threshold (noun)
the time at which something is supposed to begin	the sill of a door; a horizontal piece of wood or stone that forms the bottom of a doorway and offers support when passing through a doorway
	the entrance (the space in a wall) through which you enter or leave a room or building; the space that a door can close
	the smallest detectable sensation
	a region marking a boundary
	the starting point for a new state or experience