Are there differences between knapsack and backpack ?
I have a Jansport knapsack or backpack ?
Recalling my Boy Scout days, I believe "knapsack" was the earlier term. It was usually a small pack suitable for a one-day hike, carrying little more than a lunch.

It seems like the term "backpack" came into use when they developed hiking packs with aluminum frames, allowing one to comfortably carry a heavier load.

Perhaps serious hikers learned of these before I did. I expect early explorers hired people to "pack" heavy loads on frames on their backs.

I believe currently, the very small packs which students use to carry their books to school, are called "backpacks."

- A.
Students: Are you brave enough to let our tutors analyse your pronunciation?
Backpack think student. Knapsack think a hiker or tourist.

anyone with the name seth or initals SAGL will always be wearing knapsacks.
I'd add that for me a knapsack (probably from knappen "to eat") is now a 'daypack'.