Are you talking about the difference between bar action locks compared to back action locks? FYI, not all back action locks are Island style. Island style locks are surrounded by wood, not touching the receiver....kinda like an.....Island! :-).
My personal opinion is that back action locks are just a bit more aesthetically pleasing to my eye than bar action. I'm weird though, I think the 2nd pattern Purdey thumb opener is uber sexy and I love the graceful and stout Jones underlever, Powell lifter actions get me all giddy too.
Some say back action is stronger as well because all of the works are behind the action, making for a solid bar. Whether or not the locks on a hammer gun are rebounding or not is significant to most people. Rebounding locks are much more convenient. Non-rebounding are just a little more work and training to work safely.
