potato beetle vs leaf beetle

potato beetle and leaf beetle both are nouns.

Word	Noun	Adjective	Verb	Adverb
potato beetle	Yes	No	No	No
leaf beetle	Yes	No	No	No

As nouns, leaf beetle is a hypernym of potato beetle; that is, leaf beetle is a word with a broader meaning than potato beetle:

potato beetle: black-and-yellow beetle that feeds in adult and larval stages on potato leaves; originally of eastern Rocky Mountains; now worldwide
leaf beetle: brightly colored beetle that feeds on plant leaves; larvae infest roots and stems

Other hypernyms of potato beetle include chrysomelid.

potato beetle (noun)	leaf beetle (noun)
black-and-yellow beetle that feeds in adult and larval stages on potato leaves; originally of eastern Rocky Mountains; now worldwide	brightly colored beetle that feeds on plant leaves; larvae infest roots and stems