How are fluorescent lamps used in tanning beds different from regular fluorescent tubes?

I believe they have much stronger UV output. There might be some IR output as well but I have no idea if there are any IR phosphors available...

The phosphors are designed so that the frequency of light emitted is primarily in the UV-A region best for tanning, though that probably overlaps a bit into UV-B territory. You will see the blue visible light as well, similar to a Blacklight lamp, but the the tanning lamps are more dangerous to look at. Not quite as dangerous to tissues as a UV-C Germicidal lamp though (which has a quartz bulb and no phosphor).

Interestingly, when I first saw a tanning bed it had 72" T12 H.O. rapid start lamps in it. I thought they were all that way in the US, but more commonly (with the older Wolff beds and probably others), they used bi-pin 72" normal output lamps, which were operated on preheat circuits. Each of the 16 or so lamps had its own starter and was operated off of choke ballasts on a 220v supply. That means in the US, you have to use a buckboost transformer to adapt the European 220v/50Hz to 240v/60Hz. But boy is it fun to turn one of those beds on and see all the lamps blinking!

Now the big thing in tanning salons seems to be the high pressure lamps, with beds either having a combination of fluorescent & HID or even all HID lamps (double-ended metal halide).

Cool! Why are they on 220volts though?

Mebbe it's for simpler ballasts. (Simpler means lighter and cheaper.) And there is a lot of those inside one tanning bed. (Biggest on ebay is 34 lamps. Although there are those where you have to stand which has 56 lamps! Definitely want to drop by those tanning salons and see those lamps fire up. (Simple choke coils means preheat.)

FGS, that's exactly it. The 220v or 240v supply voltage means cheap choke ballasts can be used, saving cost. Now with electronic ballasts, it's not as big of a deal.

I think the Wolff beds were made in the UK and thus were 220v/50Hz but I'm not sure.

Interestingly, the Sears tanning lamp I used to have used a high pressure mercury lamp with a heating coil in back of it that functioned both as a heater (so it felt like you were in the sun) and a ballast! The lamp was started by holding a switch down until the filaments in the mercury lamp ends lit, then you released the switch and the arc struck - like a manual-preheat fluorescent. But it had a good 5+ minute restrike time.