The difference is that I replaced the Sheffield in my Peavey 112E extention cab with a Made-In-England Celestion Greenback and now the cab is not only usable, but sounds good
honestly though, sheffields are garbage. i played a peavey JSX through a peavey cab with sheffields in it at a store yesterday, and i wanted to kill myself. i switched to a marshall with celestions and it sounded amazing. every amp i've played with sheffields has sucked.