Coupling is used to obtained permanent connection between driving and driven shaft, while Clutch is used to connect & disconnect driven shaft from driving shaft.
Coupling is used in application where driven machine required continuous service, while Clutch is used to transmit power between two co-linear shafts.
Muff coupling, flange coupling, universal coupling and Oldham coupling etc. are examples of coupling, while jaw clutch, disc clutch, cone clutch and centrifugal clutch etc. are examples of clutches.
