The differences between the terms ‘backpack‘ and ‘rucksack‘ often differ themselves, depending on who you ask. What I have learned from my many, many dedicated minutes spent intensively googling the subject is that it is amazing how many capably intelligent people can completely disagree on even the simplest of subject matters. You will discover my findings beneath the back-pack and/or ruck-sack images below.
Camping Backpacks & Camping Rucksacks Available on EDIT:
Origins of Rucksacks & Backpacks
The word rucksack is definitely European based and translates into English directly from German as backpack. It is used far more commonly in the UK than the US and originally derives from the German for back, rücken. The post-fixed ‘sack’ has been word-napped before for other bags such as the single shoulder-strapped Haversack and the Knapsack, which is usually (though not absolutely) a smaller version of the backpack. The combined term rucksack has been suggested to be ‘perhaps 150 years old’ though how much basis in actual fact that statement has I have no idea.
The differences between their appliances do have a military origin in that the ruck-sack was a back-pack that had a frame attached to it – so soldiers could carry extra supplies for longer treks and expeditions. A frame-strengthened ‘rucksack’ would also have had more attachments for cooking materials and camping equipment. It rings true in other accounts that the rucksack was a type of backpack, though there is debate over whether the rucksack had a frame or was simply a top-opening backpack that was neither too small to be a purse or knapsack, nor too big to be considered as a hard-framed expedition-pack.
There is another school of thought that the newer term backpack is essentially a form of rucksack, being a top-opening bag with two straps for the shoulders.
Regardless of the theory, in practice both terminologies are correct as both modern usage and the fact that most hard-framed bags are gone now, save for the really big expedition packs, as serious backpacks and/or rucksacks have internal stiffening. So ruck or back, pack or sack, it’s up to you. Ruckpack or backsack anyone?