rucksack vs knapsack

rucksack and knapsack both are nouns.

Word	Noun	Adjective	Verb	Adverb
rucksack	Yes	No	No	No
knapsack	Yes	No	No	No

As nouns, rucksack and knapsack are synonyms defined as:

rucksack and knapsack: a bag carried by a strap on your back or shoulder

Other synonyms of rucksack include back pack, backpack, haversack, packsack.

rucksack (noun)	knapsack (noun)
a bag carried by a strap on your back or shoulder	a bag carried by a strap on your back or shoulder