millstone vs loading

millstone and loading both are nouns.

Word	Noun	Adjective	Verb	Adverb
millstone	Yes	No	No	No
loading	Yes	No	No	No

As nouns, loading is a hypernym of millstone; that is, loading is a word with a broader meaning than millstone:

Other hypernyms of millstone include burden, load.

millstone (noun)	loading (noun)
one of a pair of heavy flat disk-shaped stones that are rotated against one another to grind the grain	the labor of putting a load of something on or in a vehicle or ship or container etc.
any load that is difficult to carry	goods carried by a large vehicle
(figurative) something that hinders or handicaps	weight to be borne or conveyed
	a quantity that can be processed or transported at one time
	the ratio of the gross weight of an airplane to some factor determining its lift