Diffrence between 2 sch 40 and @ sch 40S pipe - Material

Q.What is difference between sch 40 and sch 40S pipe,as both of the dimensions like OD,ID & nominal Thickness are same.?

Schedule 40 Stainless Steel Pipe

457.2mm Sch 40 Sch 40s 20FT Stainless Steel Industrial Tube - China Industrial Pipe, ASTM A312 Tube

Stainless Steel Seamless SCH40s Pipe - 153.0976.02

A312 TP316 Seamless Pipe, SCH 40S, PE, 1 1/2 Inch - Landee

ASTM A312 TP304 Seamless Stainless Steel Pipe and SA312 304 ERW Pipes

UNS S31803 Steel Pipe,Pipe Fittings,Flange

High Wall Thickness SS 316/316L Seamless Pipes, SCH 40S, 80S, XXS

KNOW THE DIFFERENCE BETWEEN SCHEDULE 40 AND 80 PIPES FOR GAS AND LPG (COOKING GAS) INSTALLATION IN NIGERIA

SP46 -SS316 Stainless Steel Schedule 40 Seamless Pipe: Full

Schedule 40/40S Wall thickness Stainless Steel Pipe - Dongshang Stainless

ASTM A312 TP304 Seamless Stainless Steel Pipe and SA312 304 ERW Pipes