They both work the same.
As far as vibration and pumps, back before there were dc pumps, we used pumps like Little Giants, Blueline, Iwaki, mag pumps, etc., and they tended to be noisy and did have a certain amount of vibration, which by using soft tubing helped eliminate.
But now since I've started using dc pumps like Vectra, Red Dragon, VarioS, I haven't noticed any vibration or vibration noise and I have been using pvc 100% of the way.
For me personally, I like the look of pvc piping when it is clean, straight and even colored.
I use hard plumbing and have no noise. But I should have (and plan on doing it) plumbed soft off the return pump at least for part of the way to allow easier movement of the pump.
If your concern is noise then I would use both, hard plumbing for the majority of your run and a short piece of silicone tubing going from the pump to the junction with the hard plumbing.
Always soft everywhere-or at least sections for stress relief. 90% of the broken tanks I have seen- and its hundreds-have been due to bulkhead and hard plumbing becoming a lever on the tank. Returns obviously are not always int a drilled bulkhead, but its always something to bear in mind- that seldom is.
Here's what I did for each of my two return pumps in sequence:
hard: pump to union
hard: union to 1" flow meter (try to keep flow meter above highest water line)
hard: flow meter to union
hard: union to nipple (these first four are all vertical)
soft: nipple to nipple (3-4 foot length with loose curve to reduce likelihood of kinking)
One line goes through chiller (soft in, soft out)
hard: nipple to shaped pvc (this section is the longest and shaped to reach the destination)
hard: pvc to union (about a foot below bulkhead)
hard: union to bulkhead (threaded: not slip)
The unions reduce the overall flow (add head pressure), but they give me ease of maintenance and break-down (if I move). The flow meters also add head pressure, but their information is most useful. I haven't cleaned my return pumps for more than a year now because my flow has remained steady at 300 gph each line. Carbon-dosing seems to help keep them flowing well. I would've never guessed that.
I don't understand your noise reference. Why would hard-plumbing be noisy for a return line that is pressurized?
My three, independent drain lines are all completely hard-plumbed and they are also quiet. The overflow itself and the height of the pipe-ends in sump control the noise level. I use an bean-animal style overflow.