tipper lorry vs motortruck

tipper lorry and motortruck both are nouns.

Word	Noun	Adjective	Verb	Adverb
tipper lorry	Yes	No	No	No
motortruck	Yes	No	No	No

As nouns, motortruck is a hypernym of tipper lorry; that is, motortruck is a word with a broader meaning than tipper lorry:

tipper lorry: truck whose contents can be emptied without handling; the front end of the platform can be pneumatically raised so that the load is discharged by gravity
motortruck: an automotive vehicle suitable for hauling

Other hypernyms of tipper lorry include truck.

tipper lorry (noun)	motortruck (noun)
truck whose contents can be emptied without handling; the front end of the platform can be pneumatically raised so that the load is discharged by gravity	an automotive vehicle suitable for hauling