Vive uses packaged low end IEMs that are the bare minimum. So you can immediately chuck those into the nearest garbage can for recycling to pick up. The OR headphones snap onto the band of the headset. You can remove them and plug your own headphones in.
For both cases though, I recommend IEMs over headphones for a couple of reasons:
1) Much more lightweight, so they are less of an immersion breaker.
2) Interfere less with the HMD headbands (unless you are talking about on-ear headphones, which get uncomfortable after a couple of hours of use)
3) I'm an IEM geek, won't lie that I'm a bit biased there !
Here is a video of the headphone removal on the CV1:
Oh, and I did forget to mention that the FOV on the Vive was actually a bit better than the OR. Noticeably better. Just the fresnel lenses on it were a bit less polished overall in design than the OR.
Edited by Kinaesthetic - 2/22/16 at 9:38pm