If careful thereafter, would a blistering sunburn in uv 11 or accumulative moderate sun exposure over a persons life time be worse? ive read its the uv exposure associated with the burn not the burn itself that is harmful?

Both : Increase incidence of skin cancer has been noted in these with severe sunburns, and the collective damage from repeated sun exposure increases the chances of skin cancers, wrinkles, and weathered skin changes. Use sun blocking/hydrating products when in sun, eat healthy foods, get adequate rest, and use skin emollients on a regular basis and don’t smoke.