Its very, very close. I mean, it's not like there was 10 points between them.
Len gave Peter an 8 and Jay a 9 and Peter danced his Jive later in the competition when they tend to award lower scores for the same level of performance.
Len is from the world of Ballroom and Latin dancing, so maybe he is more focussed on technique than performance, so that his why he could see the slight difference in technique between Jay and Peter.
I guess it comes down to taste. It doesn't mean one of them danced better than the other.