Both have exactly the same features. The difference lies here: Admin Pages PRO is a stand-alone plugin, while Admin Page Creator is a WP Ultimo (another plugin from NextPress) add-on. This means that Admin Pages PRO does not rely on any WP Ultimo code, and can be used regardless of that plugin, in single or multisite installs. On the other hand, as an add-on, Page Creator uses WP Ultimo code, only works when WP Ultimo is active, and only supports multisite.