Ah right, an extra feature then (surprising in the cheaper filters), and not to do with holes vs louvers. Thanks for that!
Since the filter mounts horizontally on the Jag's engine block, I guess the standpipe doesn't really make much difference there.
I compared six models of oil filter that I've used on my 1989 Jaguar XJ40 (4L straight 6 engine) over the years, posting full details at this Jaguar forum (bits of metal are (mainly?) from cutting open the cans with a reciprocating saw):
Models shown (left to right):
Baldwin BT364 (made in...