Why no separate activities for hiking vs backpacking?

Because even the distinction between Hiking and Climbing is not really clear...

I agree with tess 

Calories is based on HR and bodyweight. Increased effort while hiking will show up in increased HR, whether this is because of speed, incline or pack weight. And increased HR will result in increased calorie counts.

The definition of the activities is a little vague anyway, so I think you may be asking too much.

SImple test, if you are hiking or walking or jumping and you are putting on weight, .........eat less and move around more :-)

One interesting example is that when I look at backpacking vs hiking in Connect I’m not seeing a significant difference in calories expended. 

This is me with ~28 pound/13 kg pack:

i.imgur.com/Odnhcpd.jpg

This is me with a ~5 pound/2.25 kg running vest:

i.imgur.com/y0LNpZo.jpg

They are relatively comparable. I’m going a little faster without that pack, and I had a little more elevation gain. My heart rates are comparable too. Should they be? Am I actually burning the same calories?

I922sParkCir said:

They are relatively comparable. I’m going a little faster without that pack, and I had a little more elevation gain. My heart rates are comparable too. Should they be? Am I actually burning the same calories?

They're more than relatively comparable. I don't know if you realize it, but you posted the same Connect snapshot for both activities. 

Thank you for the catch!

Disagree with this.  There must be some correlation between pack weight and calorie expenditure.  Simply adding the pack weight to your body weight in Garmin settings during the exercise changes the calories burned.  That is essentially what a heavy pack is doing albeit over a short duration. 

Example of one study: www.outsideonline.com/.../ultimate-backpacking-calorie-estimator

singletrackmind said:

There must be some correlation between pack weight and calorie expenditure.

Where can I find something about heart rate in the study? Is this not considered there? You have to take into account that our watch calculates this. 

6184211 said:

Seems like there should be an option to input estimated pack weight and have that influence the estimated number of calories burned.

The“terrain factor” is also taken into account in the study you have linked : 

“terrain factor” that adjusts the results for different surfaces (for example, a paved road has a terrain factor of 1.0, but a gravel road is 1.2, since it takes more calories to walk on a soft or uneven surface)

Why do you limit yourself to the weight of the backpack?

singletrackmind said:

Disagree with this.  There must be some correlation between pack weight and calorie expenditure.

You say you disagree, and then you go on to repeat exactly what she said...

Yes, you burn more calories when carrying a heavy backpack - and also YES the watch already accounts for this. It knows you're burning more calories with the backpack, because of your increased heartrate. It doesn't know that the reason why you're burning more calories than usual is because of your heavy backpack, but that doesn't matter. The watch doesn't care why you're burning more calories. All it knows is that you are, in fact, burning more calories - again, based on higher than usual heartrate.