difference between duplexer and diplexer

see https://www.edaboard.com/viewtopic.p...light=duplexer and
https://www.edaboard.com/viewtopic.p...light=diplexer
and then use the search of the forum and perhaps you will find immediately the answers at your questions.
Regard

Diplexer: can handle two diferent frequencies, just when
you use it to couple a single antenna to two or more transmitters
of different frequencies.
Act more like a combiner of different frequencies.
when receiving the diplexer separates the two frequencies
just like having two filters in parallel
Ex: cable and antenna combiner/splitter

Duplexer: can handle one single frequency, just when
used to couple a receiver and a transmitter of the same
frequency to a single antenna.
Act more like a circulator
In transmission the signal does not goes to the receiving path
just to the antenna. In receiving the signal does not go to the
transmiting path.
Example: Radar, same frequency but needs separation of
receiving path and transmiting path while using the same antenna.

So:
Diplexer = Combiner; two frequencies
Duplexer = Circulator; single frequency

some people call a duplexer a diplexer when use a "split". This is
not a duplexer. Esentially this is a diplexer with smal separation in
transmit and receive frequencies, they called this separation the "split"

Actually a duplexer can be two different frequencies too. In this case, one antenna is used for both transmit and receive at the same time. For example, you have a duplexer in your cell phone. In the case of radar, typically, the reciever is turned off during the transmit pulse.

This might be helpful.
http://www.temex.net/temex/technote/dup_dup.html