Will covering 8Km in an Hour and 2 Hours burn the same amount of calories?

It will be very similar, but with regard to the same distance running does require marginally more energy than walking. It depends on your weight, current fitness levels, and the intensity or speed for each. Sprinting 1 mile can burn more than a light jog for one mile, and power walking 1 mile will burn more than a leisurely pace for one mile.

https://www.livestrong.com/article/314404-how-many-calories-do-you-lose-per-mile/ says:

"You can calculate your total calorie burn per mile of walking by simply multiplying your weight by 0.53. For instance, if you weigh 200 pounds then your total burn would be 106 calories per mile, but if you weigh 175 pounds, you will burn a total of 93 calories. A 125-pound person will use even less energy, burning about 67 calories per mile of walking.
...
If you run you'll burn more calories per mile than you will walking. The formula for total calories burned per mile of running is 0.75 times your weight in pounds. At this rate a 200-pound person burns about 150 calories per mile. A lighter 175-pound person will burn 131 calories per mile, while a 125-pound person will burn just 94 calories per mile."

TimeToReduceFat wrote: »

One will be running & the other will be walking.
Thank you.

No, you will burn more calories running.

Tacklewasher wrote: »

Rule of thumb for calorie burn is
Running Weight X distance (miles) X .63
Walking Weight X distance (miles) X .3

If you walk or run the same distance, you will burn about 2X the calories running. How long it takes doesn't factor in.

^^ This.

Running always burns more calories per mile than walking the same distance. The reason behind it is the energy required to make the movement, since they require a different gait/movement style.

Walking requires forward motion, with one foot on the ground at all times. Running requires a forward and upward motion, as part of the gait has both your feet off the ground at one point in each step. The required energy to lift your whole body up off the ground (even if it's only a few cm) means that running will always burn more calories per step. Even if you run a very slow 1km, then walk a very fast 1km so that you're actually going at the same pace, you'll still burn more calories during the run.

Exception: I'm at work and can't find the study, but supposedly there is a walking speed that, when reached, burns more calories than running because of how you have to alter your gait to physically walk that fast. But you'd be at an olympic style walking pace to reach that kind of speed I'm guessing.