What is the difference between a coupler and a splitter?

A coupler and a splitter are both used to connect two devices together, but they function differently. 

A coupler is a device that connects two cables or wires together. It is generally used to join two cables of the same type or to extend the length of an existing cable. A splitter, on the other hand, is a device that is used to divide a signal into two or more parts. It is commonly used to split a signal from one device into multiple devices, such as a television signal being split between two TVs. 

A coupler is a passive device, meaning it does not require any power to function. It simply joins two cables together, allowing the signal to pass through without any alteration. A splitter, however, is an active device, meaning it requires power to function. It is used to divide a signal into multiple parts and can be used to amplify the signal as well. Couplers and splitters are both used in various applications and can be used to connect different types of devices together. 

However, they serve different purposes and should not be confused with one another. A coupler is used to join two cables or extend an existing cable, while a splitter is used to divide a signal into multiple parts.