tanker vs tank truck

tanker and tank truck both are nouns.

Word	Noun	Adjective	Verb	Adverb
tanker	Yes	No	No	No
tank truck	Yes	No	No	No

As nouns, tanker and tank truck are synonyms defined as:

tanker and tank truck: a motor vehicle designed to carry liquefied loads, dry bulk cargo or gases on roads.

Other synonyms of tanker include tanker truck.

tanker (noun)	tank truck (noun)
a cargo ship designed to carry crude oil in bulk	a motor vehicle designed to carry liquefied loads, dry bulk cargo or gases on roads.
a motor vehicle designed to carry liquefied loads, dry bulk cargo or gases on roads.
a soldier who drives a tank