Apart from the number of servers (1 vs 2), the main difference between Oracle Database Appliance lite (S/L) and High-Availability (HA) is the data disks location. They are inside the server on lite ODAs, and in a dedicated disk enclosure on HA ODAs. Obviously, this is because when 2 nodes want to use the same disks, these disks have to be shared. And this is why HA needs a SAS disk enclosure.
Disk technology on ODA