You need to put more effort in 1 hour cycling session to burn the same amount of calories as in 1 hour running session. Running activates more muscles.
I was "professional" athlete many moons ago. When we measured max heart rate, we did it on a bike first and then on a treadmill running and then bike again. My max heart rate running was +5 beats allways and I was not a single case. I just couldn't get to my max heart rate while cycling.