[8125, K-JAM, P4300, MDA Vario ROM Development] mfrazzz:
Ok, let me take a shot at this...

15.2.318 Build 15341 is an "Official" Wizard WM6 rom with a date of February 2006. This is the basis for the Faria "the real thing" rom and his Kitchen. This is a Microsoft "Dogfood" rom, (ie: Microsoft was building WM6 for devices that didn't exist yet, so they used an existing device (the Wizard) to do initial development work, and this was one of those roms. The Faria version is the only version of this rom I'm aware of, and while it was not a port from some other device (it was created for the Wizard), Faria modified it to work better.

15.2.318 Build 15342 (InGeNeTiCs) is a newer "Official" Wizard Wm6 rom with a date of August 2006. Again, this is a Microsoft "Dogfood" and we came about getting this rom from a guy that came over from HowardForums named InGeNeTiCs (thus the name giving him credit). There are many forms of this rom. The initial form of this rom was straight off his phone, and could not be used on any other device (supposedly he got this upgraded by someone at Microsoft) as it had stuff to make sure it was running only on his phone. After some hacking we figured out how to remove this. There was a rom released with only this stuff removed, and then I released a version that had that removed, some other phone home stuff I found, and added in MMS and a few other things to make it more usable. This was a "beta" build but turned out to be very fast and stable (Seemed faster than the Faria 'the real thing' and the Faria vanilla in the kitchen) and had MUCH better battery life. There are many that still run this as their base rom.

Numerous other roms started coming out at this time based off if this build, after I released XM6, and mattk_r started producing a base and oem packages for it in his Ingenetics kitchen. Note, XM6, mattk_r's stuff, and most of the others are based on InGeNeTiCs, but a lot of things have been upgraded and replaced from various places, so the base may be "official" but a lot of the guts have been replaced from other places. To me (IMO) this is a VERY stable rom for a base, and why I build on it (same with Faria's 15341 vanilla).

Faria then released his latest rom which turned out to be the same build (15.2.318 Build 15342). It is NOT based on the InGeNeTiCs work, as its a rom he had and had worked on (he had hinted earlier he had something newer but couldn't release it, and I'm guessing he released it once he saw the InGeNeTiCs one had been leaked and broken). Again, this is a Faria build, so it has been tweaked and all with his spices and herbs. Good rom, but I didn't feel it was as fast or had as good of battery life as the InGeNeTiCs version (not sure why).

Any ROM after 15.2.318 so far (so 15.2.1413 is included) are ROMs that are for other devices, that have been reworked to work on the Wizard device (I think most of these were done by mUn). A lot of the internal parts of WM6 seem to be the same, but newer roms, had newer add on features and stuff (Office 2007, Arcsoft 4.0, newer Camera, etc). I'm sure there are probably bug fixes in later builds, but I think a lot of the later builds are more for supporting newer hardware (3G and stuff). Some of the newer builds have been made very stable by excellent chefs (Xplore is a prime example of this. The mUn rom was very good, but had numerous issues with Wifi and the like. Xplore is a very fast and very stable version of that rom build now).

So the main difference has to do with anything after 318 is a port of a rom from another device. Not necessarily bad, but usually it means there will probably be some quirks with it since its not native for the Wizard (some of the internals may not match up with the drivers and such that we have available). But there are some great roms built off of 15.2.1413 and while I haven't played with any (yet) since I've focused on 15.2.318 recently, Newer things like TouchFlo and all seems to work better (although I think Whiterat and mattk_r have resolved some issues in 15.2.318 and TouchFlo is now working well there, but still in beta).