field trial vs trial run

field trial and trial run both are nouns.

Word	Noun	Adjective	Verb	Adverb
field trial	Yes	No	No	No
trial run	Yes	No	No	No

As nouns, trial run is a hypernym of field trial; that is, trial run is a word with a broader meaning than field trial:

field trial: a test of the performance of some new product under the conditions in which it will be used
trial run: trying something to find out about it

Other hypernyms of field trial include test, trial, tryout.

field trial (noun)	trial run (noun)
a test of young hunting dogs to determine their skill in pointing and retrieving	trying something to find out about it
a test of the performance of some new product under the conditions in which it will be used
a contest between gun dogs to determine their proficiency in pointing and retrieving