You must definitely burned calories while on the elliptical, certainly more calories than you burn just sitting on the sofa. Whether or not you burned as many calories as you would have on the treadmill depends on whether or not you achieved the same elevation in your heart rate. Did you feel like you were working as hard as you do on the treadmill. Not just that your legs felt rubbery, but were you as out of breath as you are on the treadmill? Did you feel like your heart was beating as hard and fast as when you work out on the treadmill?
A good way to evaluate how hard you are working is the
perceived exertion scale. If you reached the same level on this scale that you normally do on the treadmill, then you were probably burning around the same amount of calories.
The sweating doesn't mean anything. I sweat a ton in the sauna and it seems like I hardly sweat at all when I'm running outdoors or swimming, but I can guarantee you that I'm burning more calories running or swimming than sitting in the sauna. The fact that you didn't notice yourself sweating just means that your body temperature was lower or that your sweat was evaporating faster (either could be a result of the air conditioning).