Appointment Plus has been around since 2001 and has gone through many evolutions and iterations. Lots of features compared had to come from the public marketing page as access was limited.
Clearly specializing in appointments for retail, logistics, government and health care and not exposing price points suggest an enterprise level software product with enterprise level pricing.
The above feature comparison was performed by our users who were Appointmentplus users, and may not be 100% accurate. If there are ammendements that you find that need to be made or if you want to confirm the existence / non-existance of certain features please contact us on firstname.lastname@example.org.