lactation vs suckling

lactation and suckling both are nouns.

Word	Noun	Adjective	Verb	Adverb
lactation	Yes	No	No	No
suckling	Yes	No	No	No

As nouns, lactation and suckling are synonyms defined as:

lactation (noun)	suckling (noun)
feeding an infant by giving suck at the breast	feeding an infant by giving suck at the breast
the production and secretion of milk by the mammary glands	a young mammal that has not been weaned
the period following birth during which milk is secreted	an infant considered in relation to its nurse