A slim fit 686 and slim fit L1 are vastly different. So it just saying "slim" doesn't mean much.
L1 is by far the greatest outerwear of all time. For me Bonfire might just be second. Or Cappel. The Cappel slims fit like L1 regulars, the Bonfire slims fit like L1 slims but the regulars are baggier than L1 regulars.