"double-strand breaks...are caused by ionizing radiation, including gamma rays and X-rays." vs. "UV radiation causes two classes of DNA lesions: cyclobutane pyrimidine dimers (CPDs, Figure 1) and 6-4 photoproducts (6-4 PPs, Figure 2)."

https://www.nature.com/scitable/topicpage/dna-damage-repair-mechanisms-for-maintaining-dna-344

Simply put: more energy in a light wave the more likely it is to cause cellular (DNA) damage.

Ultraviolet has less energy than X-rays (it goes through your flesh to see bones!)

Order of light strength (cell damaging capability)

• X-Ray > UVA (also able to cause double strand break) > UVB (most likely single strand break - repaired)