island vs safety island

island and safety island both are nouns.

Word	Noun	Adjective	Verb	Adverb
island	Yes	No	No	No
safety island	Yes	No	No	No

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

island: a zone or area resembling an island
safety island: a curbed area in a roadway from which traffic is excluded; provides safe area for pedestrians

Other hyponyms of island include kitchen island, safety isle, safety zone, traffic island.

island (noun)	safety island (noun)
a zone or area resembling an island	a curbed area in a roadway from which traffic is excluded; provides safe area for pedestrians
a land mass (smaller than a continent) that is surrounded by water