The Focus 160's are bigger, heavier, wider range, fuller, and easy to listen to for hours on end. The Emit M10 is, I think, really designed for smaller spaces(dorms, small bedrooms, small condos, small apartments, desktop use).
The Focus 160's were more expensive than the so-called entry level Emit speakers. Dynaudio no longer makes the classic Focus. The Contour 20 may be the closest model in the current lineup, but for more money still. The newer Focus XD speakers are all powered and have DSP-based crossovers - quite a different beast.
The Excite series is also worth looking into if you're considering digging deeper into Dynaudio's offerings. The company makes a lot of different speakers.
Anyway, if you happen to find a used pair of Focus 160's, they're worth a very intensive audition. They can go head to head, on most material, with the KEF LS50, Bryston Mini-T, and can even duke it out on some material with the likes of the Kudos Cardea Super 10 (3X the price, mind you, and one of the best standmounts you can buy), the Joseph Audio Pulsar on quite a bit of music, and a variety of other competing serious standmounts in the $2,000-$5,000/pair range.
The Focus 160 (and the Contour 20 and the Excite X18) are all much more versatile choices than the Emit 10. It depends mostly on what you listen to now, and what you're planning for the future, and the actual system you've got in mind.