One is an early bronze fork, the other a later steel fork. That said, I've never compared the two side by side to see if they're different lengths. I do know that to use the steel fork in an old style side cover there are ends on the fork (shaft) that have to be trimmed off. It doesn't usually leave as pretty of a surface as the one in your photo which looks cleanly machined. Possibly the fork is from some other brand ??