The main EMT fittings are EMT connectors and EMT couplings.
What’s an EMT Connector?
An EMT connector always comes with a lock nut at its threaded end. EMT connectors are designed to slide over an Electrical Metallic Tubing at one end, and tighten down to the inside of an electrical box at the other end.
What’s an EMT Coupling?
EMT couplings are the same on both ends. An EMT coupling is for use to join two lengths of Electrical Metallic Tubing together.
Overall, you will use both EMT connectors and EMT couplings in each EMT raceway.