
Salomon are generally a "better" make. They tend to use stronger/lighter/more expensive materials and are of a better build quality.
BUT,
Looking at the two items you have picked out...
I recently bought a Field and Trek "Stormlite" branded bag, very similar to that style and have found it absolutely fine. For packing up and throwing in the car it's great- strong, weatherproof and easier to pack than a rucksac, plus it fits better in a car boot. Id say, as long as you dont intend to use the bag as a rucsac for more than 2 miles of walking, the cheaper option is perfectly fine.