Sorry Frank, but I think your summary is not correct. Let me try to sketch my own summary:
Filter Out All SubVersions = Show Main Versions and non-versioned images
Filter Out Redundant SubVersions = Show non-versioned images + Qualifying Versions
(Qualifying Version = Main Version, if present in the current collection; otherwise: one of the displayed sub-versions)
Please note that the two scripts have the same effect if and only if the versioned images in the current collection include all the corresponding main versions.
(Sorry, I've found no simpler way to summarize the functionality. Hopefully, an example will clarify it.)
Let's say Img_Main, Img_SubVersion_1, Img_SubVersion_2 is a version set and Img_NonVersioned is a non-versioned image.
Case 1: current collection shows all 4 images: (Img_Main, Img_SubVersion_1, Img_SubVersion_2, Img_NonVersioned)
Filter Out All SubVersions: displays (Img_Main, Img_nonVersioned)
Filter Out Redundant SubVersions: displays (Img_Main, Img_nonVersioned)
Case 2: current collection shows: (Img_SubVersion_1, Img_SubVersion_2, Img_NonVersioned)
Filter Out All SubVersions: displays only (Img_nonVersioned)
Filter Out Redundant SubVersions: displays (Img_SubVersion_1, Img_nonVersioned)
Please note that both filters satisfy the fundamental filtering property: the filtered collection is always a (strict or non-strict) subset of the initial collection.
Does that make sense and match your experience?