At present, the commonly used materials for backpacks are "nylon" and "Cordura". Although canvas is wear-resistant, it is rarely used because it is easy to get wet, difficult to dry when wet and heavy. Nylon cloth has light weight, no moisture absorption and mildew, fast drying and good strength; The disadvantage is that it is not wear-resistant and afraid of fire. Cordura cloth is also a kind of synthetic nylon cloth, but its wear resistance and strength are better than that of nylon, and it also has no moisture absorption, no mildew, no adhesion to snowflakes and quick drying, but it is slightly heavier than nylon.

The outer materials of the backpack mainly include 420D Oxford nylon, 1000D nylon, 600D or 1000D polyester, or 1000D CORDVRA. 1000D material has high density and wear resistance, which is very suitable for outdoor use. CORDVRA is a famous high-grade wear-resistant nylon roving fabric developed by DuPont company in the United States. The wear resistance of this material is much higher than that of ordinary nylon or polyester, and it is light in weight. More than 90% of the world's famous backpacks are made of this prestigious nylon material. These materials can withstand the water pressure of 0.5m~2m to keep the items in the bag dry. Some materials also have anti-tear function, once punctured, the breach will not tear and expand.

To tell the truth, these are all picked online. I haven't tested them, and I don't know if the merchants are explaining themselves.

But the difference between canvas and nylon should be correct. There are many kinds of nylon.