loading vs span loading

loading and span loading both are nouns.

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

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

loading: the ratio of the gross weight of an airplane to some factor determining its lift
span loading: the ratio of the weight of an airplane to its wingspan

Other hyponyms of loading include power loading, wing loading.

loading (noun)	span loading (noun)
the labor of putting a load of something on or in a vehicle or ship or container etc.	the ratio of the weight of an airplane to its wingspan
goods carried by a large vehicle
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