Hi Neil, The differences between them are: SJ: different leather pattern which adds more support to the heel area, has its own (north west last I think?) last which has more room throughout and particularly in the height of the toe box. SD: sleeker, lower profile and dressier without the added panel support of the SJ. The Bounty is a made up name by bakers for a highbrid between the both, it's the smoke jumper using the SD last and you can also get the lace to toe option on them. Hope that helps. J.