laddie vs sonny boy

laddie and sonny boy both are nouns.

Word	Noun	Adjective	Verb	Adverb
laddie	Yes	No	No	No
sonny boy	Yes	No	No	No

As nouns, laddie and sonny boy are synonyms defined as:

laddie and sonny boy: a male child (a familiar term of address to a boy)

Other synonyms of laddie include cub, lad, sonny.

laddie (noun)	sonny boy (noun)
a male child (a familiar term of address to a boy)	a male child (a familiar term of address to a boy)