There are specfications for Ultrabook qualification
Most ultrabooks have 1366x768. Pretty much only needs ULV chip and relatively long battery life to be considered an ultrabook.
There are requirements as established by Intel
Intel requires manufacturers to meet certain specifications in order to market a laptop as an Ultrabook. These requirements change with each release of Intel's mobile platform."
Used to be based on CPU, Battery life, Hibernation speed (awake)
Now there are several factors in place.