ladybird vs lady beetle

ladybird and lady beetle both are nouns.

Word	Noun	Adjective	Verb	Adverb
ladybird	Yes	No	No	No
lady beetle	Yes	No	No	No

As nouns, ladybird and lady beetle are synonyms defined as:

ladybird and lady beetle: small round bright-colored and spotted beetle that usually feeds on aphids and other insect pests

Other synonyms of ladybird include ladybeetle, ladybird beetle, ladybug.

ladybird (noun)	lady beetle (noun)
small round bright-colored and spotted beetle that usually feeds on aphids and other insect pests	small round bright-colored and spotted beetle that usually feeds on aphids and other insect pests