is there any difference rom wise ? does all the software listed in both dev. section work with d821 ?

I have an HTC One M7 lvw, is it different from vzm? Will the Custom Roms and Stock rom of vzm work on my lvw?

Help please

Hello !
I'm looking for a solution to pair two bluetooth headset (or one bluetooth headset and one wire headset) to the same phone and then being able to speak between the two headsets.
I would use it like an intercom, but without the need of two phones.
Does anyone knows if it is possible and if there is an app for this ?
Thanks in advance, king regards
Vince