The exome is the part of the genome containing the instructions for making proteins: between 1% and 2% of the total. Whole exome sequencing (WES) reads only that part; whole genome sequencing (WGS), used for Ultra, reads virtually the entire genome.
The rest of the genome is not ‘junk DNA’: it includes regions that regulate when and how strongly each gene is activated, and many health-related variants are found there. In addition, if you keep your sequencing data, it will remain useful as science discovers new associations.