What is the difference between expensive sunscreen and cheap sunscreen?

Back in college, hmm

It was such a long time ago, though.

At that time, I was rather obsessed with cosmetic manufacturers.

I think I also alternated between using sunscreens from Lancôme, Dior, Shiseido, etc.

So I don't know if it protected my skin a bit in my younger days, but perhaps I chose my own path during the process of studying and getting a job after graduating from college.

I didn't go out of my way to buy expensive things like sunscreen.

Moreover, there are also more roadside shops.

You could easily get sunscreen anywhere.

Now that I'm older, I actually slather on cheap products.

But here's the thing.

I'm curious.

What is the difference between expensive and cheap sunscreens? I want to settle on a decent sunscreen.