Don’t confuse XOA (the official appliance) with xen orchestra built from sources. Official appliance has it’s own versioning for the entire thing, this doesn’t match with the xo-server/xo-web versions included in it.
Script doesn’t install XOA, it compiles xo-server and xo-web which essentially make xen orchestra. Official appliance has some additional features which aren’t available when built from sources (such as built in upgrade functionality etc).