What’s the difference? Some sources of info I found interesting are listed below, each is a relatively long read. I understand the Jamieson and Smith’s, but there is only one picture comparison that I really get there, the one with the fair isle motives; I cannot detect much difference (in fact, any difference) in the comparison between the lace samples.
I list the link in the order in which I think they work best (from fibre to yarn).
Hilltop Clouds on Woollen vs Worsted.
Jamieson and Smith’s blog on Woollen vs Worsted
Sue Blacker (Blacker Yarns) on Woollen vs Worsted
Brooklyn Tweed on Woollen vs Worsted