Quality of Nylon
The quality of nylon ranges from 400D to 1680D. At 1680D, nylon is extremely strong, tear resistant and long lasting.
In general nylon is a stronger material compared to polyester.
At the same denier count eg 600D nylon versus 600D polyester, nylon is generally 1.4 times stronger.
For this reason, nylon is usually more expensive than polyester.
Nylon with the days of cotton past, nylon has become the go-to material for backpacks.