What’s the main difference between IP version 4 and IP version 6? or Can someone explain the key diff

IPv6 has jumbograms! Okay, maybe not a daily use case, but huge packets (over 65KB) are possible. IPv4 can’t do that.

Security-wise, IPsec is mandatory in IPv6 (but optional in IPv4). So yeah, safer by design.

Still, the difference between ip version 4 and ip version 6 feels academic until your ISP finally flips the switch.