Standard Pipe Coupling
Standard male, small end inside, coupling used to join two pieces of pipe. (All fittings will fit pipe without the use of couplings.)

Fitting Coupling
Standard female large end coupling used to join to fittings together. (All fittings will fit pipe without the use of couplings.)

Material Handling Coupling
Standard female large end, to male small end, coupling used in joining pipe for material handling applications.