This filter or that

There is only one word that describes my confusion right now..

E-I-S-H

I've read an earlier topic on filtration, and as a newbie I would like to ask what the difference is between a
"Canister filter"
"HOB filter" &
"Hang on filter".

My filter is in the hood of my tank, i.e. the water get's pumped up into a small area in the top where is pours through the filtration material, and then pours back into the tank. Been running perfectly fine for 2 months now. I also am aware that the "Beginner KIT" tanks that comes with everything usually don't have the best of pumps etc, and I am anticipating my pump packing up within the next 12 months. (It's a Boyu tank).

So any information will get me in the right direction when I do need to replace.

Oh, and is under gravel filters any good? How do they work?

 

a Canister filter is an external filter that is connected to the system with pipes and it has its own pump within the filter.

"HOB filter" and "Hang on filter" is the same thing as far as I am concerned. HOB stands for hang on back. You will probably not use these if you have a canopy.