What are the display assembly differences
What's the difference between iPhone 6s LCD Screen and Digitizer Full Assembly - Choice and iPhone 6s LCD Screen and Digitizer Full Assembly?
It's a quality difference. The lower cost one is built with aftermarket parts (Tianma LCD, thinner flexes, not CPG assembled?) while the expensive one is built with OEM/Original parts and likely CPG assembled. This can be a very murky distinction that I don't want to speculate on. Matt (@cvneutron) from iFixit can certainly give you more details.
I don't see the price difference near $100. Can you link to the two prices from both the pages?
Looks like one comes with the tools you need as well as some of the parts that transfer over. If you lack the tools required for the repair then go for the tools. The parts that transfer over should be no big deal to transfer. Keep your screws organized and go slow. Good luck!