Physical layer wire performance hasn't changed between router versions. Since the G3100 has more processing power and memory, it may perform better when many devices (wired or WiFi) are transferring lots of data. There are no changes to the wired network interfaces.
CAT5e vs CAT6 makes no difference for 1Gbps Ethernet at the distances encountered in the typical home. A CAT5e patch cable performs exactly the same as a CAT6 cable. There are plenty of articles on the web about "cat5e vs cat6."
In addition to the discussions on this very forum, a google search for "G3100 review" provides info you may find helpful. There's been lots of discussion of the G3100 over on dslreports.com, too. You can find lots of user feedback and detailed Q&A there. https://www.dslreports.com/forum/vzfiber