On Monday, July 3, 2017 at 7:55:47 AM UTC-6, Gerald Kelleher wrote:

The sun is always at the center of the planetary loops so the resistance to the
partitioning of retrogrades between the inner and outer planets by perspectives
is dismaying although so little effort is put into this type of astronomy it is
understandable.

Since inner planets are always in the same half of the sky as the Sun from an
Earth-centered perspective, yes, their apparent motion has different properties
than that of outer planets. So their retrogrades will take a different form.

The ultimate cause in both cases, though, is that the Earth is one of the
planets, and also moves around the Sun. So I think that it is felt that the
differences between apparent phenomena here are not very important to dwell
upon, and assigning major significance to them risks being a regression to a
geocentric view of astronomy.

John Savard