Like the ADO15 Minis, the later (starting 1962) ADO16s appeared with several brand nameplates. Mechanical differences aside, from a design perspective we find a case of "badge engineering" -- largely superficial detailing differences intended to denote brand identity as cheaply (in tooling costs) as practical. The Wikipedia entry dealing with the ADO16 lines is here.
Besides the higher-volume production Austin and Morris ADO (British Motor Corporation's Amalgamated Design Office) 16s, that platform was used for the lesser BMC brands MG, Riley, Vanden Plas and Wolseley.
Morris and Austin 1100s featured different badges and grille bars, but otherwise looked the same.
Use of a version of MG's traditional grille required some slight changes to the hood and front sheet metal. The car shown in the press release photo also sports a two-tome paint job.
The Kestrel's side chrome strip is the same as the MGs. Front end changes accommodate a slightly stylized traditional Riley grille plus the side "whisker" treatment carried over from the earlier Mini-based Riley Elf.
This more sombre appearance was intended to denote a top-of-the-line, dignified 1100. Aside from the side strip being painted, the Princess got a slightly different hood, grille and lighting treatment.
Wolseley's changes are more in line with the Riley's. Yet again, BMC stylists were allowed hood stamping adjustments. The grille openings and light placements are nearly the same as the Kestrel's, again minimizing tooling expenditures.