That pretty much sums it up. A lot of the difference depends on your platform. In the RC world and EC world, which both center around beeps and squeaks type stuff, the EWO has a much more involved role in the mission since they are the mission. In these communities the nav isn't doing a whole lot since the majority of the flying is high-level orbits.
In AFSOC, the nav is very involved with the mission planning, and with the "flying" of the mission (i.e. directing and backing up pilots, monitoring/talking on radios, fuel calculations, etc.) EWOs are there to make sure you don't get your ass shot off. Meaning unless you're in bad guy land, the EWO isn't doing jack (i.e. no one is shooting at you when you're flying CONUS).
This is similar in the BUFF as well from what I've heard.