Chris Jones
Senior Member
how???
better clutch?
lighter?
Better (sealed) clutch, better (one piece) bail arm, different bearings (much smoother), better line lay, all metal spool and just generally better made with higher quality components. I prefer the solid metal single handle on the 4000D too, although it took a bit of getting used to when I've used Shimano double handles for so long. It is also fractionally lighter, but not enough to worry about.
Whether it's worth the extra is open to debate but I'd be very surprised if you couldn't tell the difference between them when compared side by side.