high-altitude vs high-level

high-altitude and high-level both are adjectives.

Word	Noun	Adjective	Verb	Adverb
high-altitude	No	Yes	No	No
high-level	No	Yes	No	No

As adjectives, high-altitude and high-level are synonyms defined as:

high-altitude and high-level: occurring at or from a relative high altitude

high-altitude (adjective)	high-level (adjective)
occurring at or from a relative high altitude	occurring at or from a relative high altitude
	at an elevated level in rank or importance