Likely the same specimen. Images were taken in current sort order. Intervals 8s and 20s.
I would put the coloring difference down to lighting and retouching (in the second image, I significantly brightened the bee as it was poorly exposed). First image is completely unretouched.
Definitely megabombus. Seems somewhat scruffy / long haired. The last two images show the large tongue.
It is not so clear in last two images that the black band is wider than the yellow, so I added the first image to show this.
On pink rhododendron
B. hortorum showing it's long tongue
a male one