Use 'sunburned' to describe skin damage caused by too much sun without protection. She got sunburned after neglecting to apply sunscreen.
Pro Tip 2/3
Pain and Discomfort
'Sunburned' often implies that the skin is not only red but also painful or uncomfortable to touch. He felt sunburned and it hurt to even wear his shirt.
Pro Tip 3/3
Temporary Condition
The term 'sunburned' describes a temporary state of the skin, usually healing over time. Her sunburned skin started to peel a few days later.