I have got 15 Flexitots and one of them has long pile. They were all bought new in May so I have no idea why they are different.
I have found that the longer pile Flexitot is more bulky but far more absorbant. I use it as a first morning nappy as Ed pees for England when he wakes up. This morning I wasn't quite quick enough and had to get my husband up at 6 so that I could change the sheets