It is/can be confusing...
The Lee Factory Crimp or FCD is neither a roll or a taper crimp, it is more like a stab crimp, but applied right at the case mouth. It is applied with a collet and not determinant on case length. There are a couple styles of dies too, some are open top and others capped. Seems caliber somehow makes the difference...
BUT, to confuse things, LEE Markets "Factory Crimp dies" as both Taper and Roll crimps in different die sets... hence the confusion.
Here is some very good information on the topic.
viewtopic.php?f=5&t=3750CW