NPT: NPT which stand for National Pipe Thread, have a 60-degree included angle and are measured in threads per inch (TPI). The taper of the threads allows for a tighter seal compared to straight threads. NPT fittings feature tapered threads, meaning the threads are cut at a slight angle to the axis of the fitting. This taper creates a seal as the male and female threads are tightened together.

BSP: British Standard Pipe (BSP) thread fittings are widely used in plumbing, hydraulic, and pneumatic systems. The thread angle is 55 degrees. BSP threads come in two main variations: BSP parallel (BSPP) and BSP tapered (BSPT). BSPP threads have a consistent diameter along their length, making them suitable for sealing with a washer or O-ring. BSPT threads have a tapered design, where the diameter of the thread decreases gradually along the length.