Nylon and polyester are both synthetic fibres that can often be used interchangeably in a variety of applications. However, nylon is generally considered to be of higher quality—it offers superior strength, elasticity, and abrasion resistance compared to polyester.
Because of this, when nylon prices fall close to or below those of polyester, manufacturers may prefer to use nylon instead, given its better performance characteristics. Comparing the two helps producers make cost-effective decisions based on market conditions and fibre quality requirements.