There are generally 2 types of sunscreens, physical and chemical. Physical sunscreens absorb and reflect UV radiation and usually contain zinc oxide or titanium dioxide. They tend not to clog pores but can be drying to the skin.
Chemical sunscreens, of which there are many on the market now, absorb UV radiation after they are absorbed into the skin. They have a greater potential to clog pores, cause acne etc. Also, many of them come in sweat-resistant or water-resistant formulas. I would recommend cleaning off sunscreen at the end of the day with an oil-based cleanser or make-up removal to remove the sunscreen completely.
Hope this helps!
Regards,
Dr. Joanna Chan