I am wiring a relay into a pump and right now they are using twist type connectors. Can I use end terminal connectors instead of twist type connectors? In which situation are end terminal connectors properly used.
There are all kinds of terminals but if you use the quick-disconnect type that will be better than a wire nut if you're disconnecting and reconnecting at times.
If the wires are inside an enclosure, you could also use a terminate the wire with ring or spade terminals and a terminal block / terminal strip the right size, which is sometimes nice because you can put a meter on the screws in the terminal strip when testing.