I must clarify, both DHMUs and DEMUs are a type of DMU. The one in my picture is a DEMU.

I think its a Diesel Multiple Unit. I read somewhere that a Diesel Hyradulic Multiple Unit has only 3 coaches. This one has more than just 3.

This is what I think the difference is (someone can feel free to correct me, I am neither...

I think its a Diesel Multiple Unit. I read somewhere that a Diesel Hyradulic Multiple Unit has only 3 coaches. This one has more than just 3.

This is what I think the difference is (someone can feel free to correct me, I am neither mechanical engineer nor an electrical engineer)
A DHMU is like a large car that uses automatic transmission. Power is hydraulically transmitted to the wheels. DMUs on the other hand run a diesel generator that produces electricty which then runs traction motors.
I guess its less cumbersome to handle electricity (which can be easily controlled by thyristors etc for speed control), than it is to manage raw mechanical power, so DEMUs are more popular.

Is it a DMU or a DHMU? What's the difference between the 2?