This is a comparison of core OS functionality and differences, handset skins and carrier tweaks aren't factored in.
If you couldn't tell from the chart above, the "differences" between Windows Phone 7 Series and Windows Mobile of yore (last week) are rather hard to quantify: it's like comparing a bed with an oven. Two very different things, for two very different purposes. Windows Mobile has had a justifiable position in the realm of business, and will probably continue to maintain a legacy install base for some time to come, but it's pretty safe to say that the days of Windows Mobile as a consumer-facing OS are rapidly coming to an end. Bring on the new!