Both versions of 303 ® Protectant, Marine and regular are the same product. It just varies as to where it is sold. Marine is usually found in places like West Marine and the other is generally found in hardware and auto supply stores.
I’ve been using 303 ® for decades on my Kevlar boat, hull, deck, hatch covers, cockpit rim, etc. Properly applied I’ve never seen an oily slick when the boat has been placed in the water. You spray it on and wipe it dry which bonds it to the surface. Takes only minutes to apply. It is primarily a UV protectant and is not petroleum based. Kokatat recommends using it on the gaskets of their dry suits and other similar products and some boat and RV manufacturers recommend it as well for use on plastics and fiberglass.
It doesn’t last forever and it is recommended that it be reapplied every 3-4 weeks if the boat is constantly exposed to sunlight. Some waxes may last a bit longer but both waxes and 303 ® are considered sacrificial UV protectants which break down under UV exposure while protecting the underlying surface. They all need to be constantly reapplied after a period of time.
All marine and automotive waxes are generally formulated to provide UV protection. I just find 303 ® to be faster and easier to apply and it’s worked well for me.