Two different words, the same thing? So how did that come about, and where did the term rucksack come from and why does the US call it a backpack?
The source of the two words
It’s likely that the US is where the word ‘backpack’ came from, after all it is a pack that goes on the back – it doesn’t need a variant of a German word to tell them that.
There isn’t really much difference between rucksacks and backpacks. People tend to use either although generally the term ‘backpack’ is more used in America and us here in the UK called it a ‘rucksack’. Further investigation suggests that in the US hikers more generally use the term backpack but then again the military use the word rucksack.
Any difference between the two products?
There are some suggestions that a rucksack is a medium sized bag used for camping hikes over a few days and a backpack is bigger and is used for longer treks but it’s difficult to find anything definitive. Comparisons between the actual products described by both of the words are more likely just to show up differences in tastes in the UK and the US. For example, if in the US backpacks tended to be larger than our rucksacks, wouldn’t that probably just suggest that Americans like a larger ‘bag to be carried on the back’ than we do?
So it doesn’t really matter, feel free to use either word and everyone will still understand you. More importantly when searching around for a rucksack make sure you search for both terms in case you miss a bargain.