These two phrases have basically the same meaning. These places are described as being glad, like a person is glad, because they have received water and are blossoming. Alternate translation: "It will be like the wilderness and the Arabah are glad and the desert will rejoice" (See: [[rc://en/ta/man/translate/figs-personification]] and [[rc://en/ta/man/translate/figs-parallelism]])
This speaks of the plants in the desert blossoming as if the desert itself were blossoming. Alternate translation: "its plants will blossom" (See: [[rc://en/ta/man/translate/figs-synecdoche]])