Elliptical vs Treadmill

OK, so I don't normally use an elliptical. I find that I struggle with it, so I tend to use a treadmill because I can stay on it longer. But I want to tone up AND work on my cardio so I figured I'd give it a try.

Sunday I used the treadmill for 25 min, alternating between 2.5 and 3.0 speeds at a 3.5 incline....I can't recall exact stats, but I think I hit a mile and burned a little more than 100 cal. I huffed and puffed and sweated, but I wasn't DYING afterward and my peak heart rate was around 153.

Monday I gathered up the nerve to get on the elliptical, and I did 20 minutes on the random hill setting, going between 100 and 110 rpms, but I only went .66 mi and burned like 30 cal, not to mention I STRUGGLED... I was out of breath, sweathing, and my heart rate was up at 170 when I checked at the end of it.

So my question is, why is the elliptical so much harder on me than the treadmill, but I went less distance and burned less calories?? And my next question is, which one should I be using??

I don't know the technical difference. I just know the same thing happens with me. I can rock out on the treadmill but fall flat on the elliptical. But I also stink at machines. Jogging or walking on the road or trail is easier for me.

I like the treadmill better because its 1). Running and 2). I feel like I am getting somewhere (even though I am not)

I hate the elliptical but when I use it I burn calories faster but I don't feel like it actually works me out. I used to do it for the added push to tone my butt, but now I do the stair stepper on the hills setting on level 10 or 11... its better for me and I feel like I am burning the calories.