testudo vs protective covering

testudo and protective covering both are nouns.

Word	Noun	Adjective	Verb	Adverb
testudo	Yes	No	No	No
protective covering	Yes	No	No	No

As nouns, protective covering is a hypernym of testudo; that is, protective covering is a word with a broader meaning than testudo:

testudo: a movable protective covering that provided protection from above; used by Roman troops when approaching the walls of a besieged fortification
protective covering: a covering that is intend to protect from damage or injury

Other hypernyms of testudo include protection, protective cover.

testudo (noun)	protective covering (noun)
a movable protective covering that provided protection from above; used by Roman troops when approaching the walls of a besieged fortification	the tough natural covering of some organisms
	a covering that is intend to protect from damage or injury