trial vs show trial

trial and show trial both are nouns.

Word	Noun	Adjective	Verb	Adverb
trial	Yes	No	No	No
show trial	Yes	No	No	No

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

trial: (law) the determination of a person's innocence or guilt by due process of law
show trial: a trial held for show; the guilt of the accused person has been decided in advance

Other hyponyms of trial include court-martial, ordeal, trial by ordeal, Scopes trial, mistrial, retrial.

trial (noun)	show trial (noun)
the act of testing something	a trial held for show; the guilt of the accused person has been decided in advance
(law) the determination of a person's innocence or guilt by due process of law
the act of undergoing testing
trying something to find out about it
an annoying or frustrating or catastrophic event
(sports) a preliminary competition to determine qualifications