stadium jumping vs showjumping

stadium jumping and showjumping both are nouns.

Word	Noun	Adjective	Verb	Adverb
stadium jumping	Yes	No	No	No
showjumping	Yes	No	No	No

As nouns, stadium jumping and showjumping are synonyms defined as:

stadium jumping and showjumping: riding horses in competitions over set courses to demonstrate skill in jumping over obstacles

stadium jumping (noun)	showjumping (noun)
riding horses in competitions over set courses to demonstrate skill in jumping over obstacles	riding horses in competitions over set courses to demonstrate skill in jumping over obstacles