Calories Burned Map My Fitness vs My Fitness Pal

I'm not a runner so will just comment on the cycling estimates....

Both those numbers are exceptionally high but you don't give many clues to get a comparison.

What speed?
What kind of course? (flat or climbing the Col du Tourmalet?)
What bike?
What standard of rider are you? (leisure rider/enthusiast/racer?)
How heavy/tall are you?

For me to get over 800 for an hour is pretty close to flat out on an indoor power meter trainer - I've got a very high VO2 max and cycle a lot. A mate who is a club record holder for 24hr races could break the 1000 cals barrier for an hour (700'ish for 40 minutes).

So my complete guess is that MFP is more accurate but still very inaccurate and high.

Try the Strava app for cycling perhaps?

That's a decent speed, I had to convert it to 18mph though!

My most recent ride at that pace gave me about 800 cals for 1 hour 24 mins but I'm significantly smaller than you (75kg and 175cm).

Your estimate seems reasonable to me. Strava mostly seems in the ballpark although do get a few anomalies from time to time. Obviously it's just an estimate - doesn't know things like head wind, riding position etc. but should be useable level of accuracy.

The MyFitnessPal category for that speed ("Bicycling, 16-20 mph, very fast (cycling, biking, bike riding") is far too wide a range to be useable IMHO as there's an enormous difference in effort between 16 & 20mph.