There's way too much apocryphal crap talked about BOVs and BPV's and how they are "different" or "how they hold or don't hold boost" or any one of a thousand other myths. It's a snap to google the technicalities and understand what exactly goes on and what their purpose is.
They are essentially the same thing in engineering intent but differ in sophistication, design and functionality. I wouldn't stress too much over which is which. A bypass valve (BPV) as its name implies, simply bypasses. A blow off valve (BOV) may only VTA or in some cases may be able do both, as in the Turbosmart, which can be set up to VTA 100%, Bypass (recirc) 100% or 50:50 of either. Hence the need to stick to one term. I think most of us in the automotive context should be comfortable with "BOV" as a generic term and assume it refers to its intent as opposed to its precise functionality or destination of discharge.
But if you want to vent 100% to amosphere (100% VTA) - legally or otherwise - then the issue is backfiriing and excessive fuel washing off the lubricant on the cylinder walls, unless you set up your ECU to cut fuel at the time of throttle lift-off. Partial (50 Bypass:50 VTA) does not encounter the same issues but the BOV must still be setup to minimize backfiring.
CP_e Standback & PNP; CP_e 3" SS Downpipe; Corksport FMIC with Top-mount K&N filter & OEM Ram CAI; Turbosmart BOV; Dashhawk; Prosport Boost Guage; JBR solid shift bushes; DBA 4000 Wiper-Slot front rotors; Hawk Ferro-Carbon HPS Street front brake pads (@ 69,000km); Sumitomo HTRZIII's in 225/45 x 18