Ignore the calories, now that we know that Wahoo ignores power data altogether. Nearly identical route (a little more turns here and there to avoid stopping in the one on the left) but
two otherwise very similar efforts three days apart. The added stress/power from the second effort is all from one section about a mile and a half long.
The CF bike spends more time north of 25mph than the steel bike-- it just descends much faster-- so the average speed jumps more than the power differential would indicate.