It should also record heart rate (and calculate calories). But that is all you get out of the Elliptical activity.
If you do not care about accuracy of the distance, and when you normally hold the moving handlebars, you could also use the treadmill activity. It will record a very inaccurate distance (i.e. it will not match the distance that the elliptical machine displays), but at least you have cadence that way. The treadmill activity uses the accelerometer that is built in the watch to calculate cadence and distance. The elliptical activity doesn't use the built-in accelerometer.