Wondering out loud...

So the other day, it seemed to me that pedaling the stationary bicycle was wa-a-ay too easy, so I really cranked up the tension on the resistance wheel, and now I find myself thoroughly exhausted—muscle-wise—after about 20 minutes.

Now I'm trying to figure out—based on the copious appearance of sweat that continues to be produced for a while after a 40-minute workout at lower resistance, and the sort-of "wobbly" feeling I experience in my arm and leg muscles after a 20-minute, mostly sweatless workout at the high resistance level—which is the better workout?

Or do they each have their respective advantages? Or is there no difference at all?

Because besides whatever other benefits that might accrue, I am aiming for "best immune system on the block," to help me in the Good Fight™.