All elements of the assessments can have enhanced passes, and the DFFT isn't the only element that makes a TOC's requirement enhanced. For example LNER are an enhanced pass TOC, they do not use the DFFT at all.
My assessments were 1 on 1 with Northern as everyone else failed on the Group Bourdon, so I got a bespoke day and got to ask lots of questions. They didn't go into specifics but said for GB their enhanced required more lines, less mistakes and less omissions than the standard. The tones test allowed less wrong numbers and required more symbols located. The computer tests required a higher result than standard. The MMI required a higher score than standard, the MMI is scored with a number which comes from both your interview and a little bit from the computer quiz you do beforehand.
So a lot of the assessments can be enhanced, so what Gareth says makes sense.