Very similar filters though.
The Interpet range come with a flowcone, you can direct the water up, out and side so it comes down the wall for extra aeration and less disturbance.
It's got a venturi system, biomedia unit, carbon and plain sponges, option to put fine filter pads in, adjustable flow AND an anti backflow valve!
Dead easy to maintain, as all the sponge media are in a cradle, you just lift em out.
The only problem I had was when I took it apart to clean the impeller chamber (once every few months, just squiggle a finger in and wipe the blades too) and my giant snail made off with the rubber support cap for the impeller post.
I got it back eventually, but in the meantime I repaired (bodged in other words) a new support cap with a chunky elastic band chopped up and threaded on.
They're lovely and quiet too, all you can normally hear is the splosh of water.
Don't bother with the PF1 for smaller tanks though, unless you have a bag of biomedia to go in. I put some Eheim Substrat balls in my PF1 in the snailtank, and it works superbly now.