[b]"What are the key differences between IP version 4 and IP version 6?"[/b] or [b]"Should I still use IP version

Short answer: Use both if you can.

Long answer: ip version 4 ain’t going away soon, but ip version 6 is where everything’s headed. The lack of NAT in IPv6 alone is a game-changer.

Tools like Wireshark can help you sniff traffic and see the diff. Also, Cloudflare has great docs on transitioning.