How do you actually buy stuff from them? The former seems to be the manufacturer, the latter presents an error page when asking about road bikes.
There are various threads on various forums around the world, of people who have had bikes built by both. The owner/operator of Triton is active on a few forums (eg http://forums.mtbr.com/bike-frame-discu ... 83688.html
From what I've read (eg http://forums.roadbikereview.com/bikes- ... 18120.html
), although I've not done it... the process with XACD is that you email their rep with your basic requirements. He sends back the engineering drawings of a frame to suit. You tell him what changes you want, he gets the drawings changed and sends them back. To and fro until you're happy with the design.
Then you pay your money, and wait for them to send you a frame that has been built exactly to the drawings you signed off on... regardless of whether or not that's actually what you want. Not recommended for people who don't know exactly what they want and don't read engineering drawings. They don't make design suggestions or recommendations, beyond ensuring that what's drawn is manufacturable.
It's widely believed / understood that XACD are the OEM for a few better-known brands, and their build quality is quite good.
It would appear that Triton do lots of trials frames, have managed to get quite a reputation for their titanium unicycle frames, have done quite a few MTBs, and will have a go at just about anything... even if they've never done it before. I think the website reflects that a bit... "we could do these kinds of bikes... but... we haven't got any photos, because we might not have actually done one yet".
It's going to be an adventure, which ever way I go