excavation vs diggings

excavation and diggings both are nouns.

Word	Noun	Adjective	Verb	Adverb
excavation	Yes	No	No	No
diggings	Yes	No	No	No

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

excavation (noun)	diggings (noun)
the act of extracting ores or coal etc from the earth	temporary living quarters
the act of digging	an excavation for ore or precious stones or for archaeology
a hole in the ground made by excavating
the site of an archeological exploration