True, but I've done both and the requirements are different depending on the kind of travel you will be doing. For bus, train or plane, I'd get a pack with wheels and a handle, like a carryon with straps.
Like this-
Eagle Creek pack

The lightweight gear backpackers carry will get ripped to shreds by luggage handling equipment and careless baggage handlers. I put my pack in a big duffle bag for protection when flying.