Looking at these paintings, I at first thought the difference between them was the photographic reproduction rather than the painting itself.
I studied the strange way the carter is riding one of a pair of horses, the group of three figures, the markings on the flank of the central cow. Eventually I saw how the rainbow is further from the tree in the upper picture, which is in London, than in the lower, in Munich. Only then did I notice the greater relative height of the lower picture. The greater clarity could be a trick of the reproduction. Colours are not always perfect.
I wondered at recreating such a complex scene. Sunlight strongly picks out the trunk of one of the trees on the right, and in both paintings the trunk is a similar shape. The upper one is much larger, 53″ high rather than 37″. Did the artist paint the same scene, happy to paint the same people, cows, trees, in order to demonstrate different light? The London picture seems to have a clearer, colder Northern light, and clearer detail, in faces and leaves.
The painting was a few decades before Newton’s work with prisms. I note the colour of the rainbow and wonder at it, I must look at what colours I actually see, rather than merely expect, next time I see a rainbow.
Only when I am writing this do I see the lower picture is the copy, not Rubens but “after” Rubens. Even then this site ascribes it to Rubens. Suddenly I see the two pictures differently. The clarity, I now assume, is greater technical skill. The upper picture is simply better.