Schedule 10 and Schedule 10S refer to two different standards for pipe thickness and pressure ratings.

Schedule 10 Pipe:

Schedule 10 is a common standard for pipes, and it specifies a relatively thin wall thickness.
The wall thickness for Schedule 10 pipes is typically lighter compared to higher schedules (e.g., Schedule 40, Schedule 80).
It is often used for applications where high pressure is not a critical factor.

Schedule 10S Pipe:

Schedule 10S, on the other hand, is associated with stainless steel pipes.
The 'S' in Schedule 10S stands for 'stainless.' This schedule is specifically designed for stainless steel pipes.
Schedule 10S stainless steel pipes have similar dimensions to Schedule 10 pipes but are intended for corrosive or high-temperature environments.

In summary, Schedule 10 is a general standard for pipes, while Schedule 10S is a specific designation for stainless steel pipes with similar dimensions but suitable for more demanding conditions. The choice between them depends on the material and the application requirements.