How much is replacing the s8 screen in 2018?

I've had my samsung galaxy s8 for two months now and recently my screen broke. The cracks are on the front and are superficial. I was looking for the spare parts on the internet and I'd like to know the difference between this ((https://www.amazon.com/HJSDtech-Digitizer-Assembly-Replacement-G9500%EF%BC%88Black%EF%BC%89/dp/B075NMQZDZ/ref=sr_1_4?s=wireless&ie=UTF8&qid=1519656701&sr=1-4&keywords=samsung+galaxy+s8+screen+replacement)) and this ((https://www.amazon.com/Samsung-Galaxy-Screen-Replacement-Repair/dp/B074835S1L/ref=sr_1_5?s=wireless&ie=UTF8&qid=1519656701&sr=1-5&keywords=samsung+galaxy+s8+screen+replacement))

Thank you.

The digitizer is the glass - the outer layer of the screen. The screen is the entire screen - all layers.

I wouldn't recommend that you do either (especially replacing the digitizer or the glass - you'll destroy the screen) unless you've already successfully done the job a few times (which means that you've already destroyed half a dozen dead screens). The difference between the temperature needed to get the digitizer off and the temperature that destroys the screen isn't much. (And replacing the whole screen is pretty much on that same level.) You also risk tearing or pinching wires, breaking connectors, leaving something unconnected, etc.

If you have insurance, pay the copay to have the phone replaced (which is probably a few dollars less than the digitizer) - it's cheaper in the long run. If not, pay a good repair shop to do it - it's still cheaper than doing it yourself, then paying them to fix what you broke in addition to replacing the screen.

How much is cost to replace S8 screen

That depends on where you are and how honest the repair shop is. The screen itself is over $200, and there's quite a bit of labor involved.