the top two are from two nLited XP ISOs, the bottom right is with the original untouched XP ISO.
Could you please tell me what those differences are ?
unless the USB flash drive in the bottom right dump is the same size as the other 3, I'm not seeing much of anything abnormal about the MBR.
The 85 DF 06|B2 21 05|87 0D 22 are bytes from the MS Disk Signature, which gets a different value every time you create the flash drive.
See the table "Structure of a modern standard MBR" here.
The 3F FE vs 7B EB difference is from the field that contains the address of last absolute sector in partition (see the table "Layout of one 16-byte partition entry" at the same page), which seems to indicate that your last MBR is from a drive that has a different size from the other 3. Likewise, the last set of difference has to do with the number of sectors in partition, which is also expected to be different if the drives differ in size.
So, all in all, I don't see anything in the MBR that is dependent on the image used, and I didn't code anything in Rufus for that either. It all seems to have to do with the size of your drive, as well as the unique disk signature, that gets created each time your format a new drive.
Are you saying you are seeing errors during the installation process of nLite images? If so, can you detail what they are?
I think I had a mail report from someone saying they had some trouble with nLite processed ISOs, but if this is confirmed, I'm pretty sure the issue is with the file content (such as a setup file that Rufus expects to find or patch and that is different from official XP with nLite) rather than the the MBR or partition boot record. I also have at least one report from someone using nLite without issues.
If someone uses nLite and experiences an issue with Rufus, I'm kind of hoping they can also investigate the difference that could be causing it. This could be done by keeping a copy of the files extracted by Rufus from official XP, and use that to replace the ones from the nLite USB until it installs. At any rate, if you see errors with nLite, please indicate precisely where they occur and what they are.