I'm assuming that the Relion was 110 points lower?
I tested mine at the vet twice, using the same blood from an ear poke. It was off by 25 once, and 30 the other time (both cases the vet's AT read higher).
It is well "known", and you'll see it in posts all over the board, that the AT will usually read 30 points higher. HOWEVER, there is one case, with a PZI user currently posting daily in PZI, where her Relion is reading consistently higher side by side with her AT meter, which is the first time I have read that here.
It comes down to this... whatever meter you use, you must have confidence in the meter, and go by what it says (As long, apparently, if it isn't the Freestyle Lite that many people have had issues with recently).
Your vet can't tell you which meter is okay to use and which one isn't okay to use. Hundreds, if not thousands of people have successfully treated feline diabetes using human meters at home to monitor BG. My cat, and hundreds at least, have gone into remission along the way. They work, they are "good enough" to do the job.
I'd stick with the Relion, and go by the numbers it give you.
Carl