Ultraviolet radiation that reaches the earth may be divided into
UVA (320–400 nm) and UVB (290–320 nm). UVA is further subdivided
into UVA I, II and III. A simplified way to differentiate between
the two types is to think of UVA as the aging radiation, and UVB
as the burning radiation.
There is little difference in sunscreens beyond SPF 15. Consider the following:

SPF 15 will allow 7% of UVB radiation through to the skin
SPF 30 will allow 4% of UVB radiation through to the skin
SPF 60 will allow 2% of UVB radiation through to the skin
Sunscreen is not a panacea for skin protection. Sun avoidance and
physical barriers remain the best approaches to minimizing the
acute and long-term effects of UV radiation. The data on
sunscreen use and cancer risk are complex, but on balance suggest
that the short-term and long-terms benefits of sunscreens
significantly outweigh their risks when used during periods of
unavoidable exposure. There’s no evidence that vitamin D
deficiency is a consequence of safe sun behaviours, and given
there are safe and inexpensive methods of obtaining vitamin
D (oral supplementation) the rationale for intentional,
unprotected sun exposure remains unclear.