Which version of HPE ESXi update do I need and what is the difference?

I am looking into updating our ESXi hosts running on Proliant DL360 Gen10 servers and I'm confused about which version of the ESXi update I need to use.

If I click the 'New* ESXi 6.5 U3 Oct 2020 - Support Gen9 Servers and forward' link on this HP page (https://www.hpe.com/us/en/servers/hpe-esxi.html), it takes me to the VMware site where there is an 'HPE Gen9 Plus Custom Image for ESXi 6.5 U3 Offline Bundle' zip file to download.

Where I'm running into confusion is there is also an 'HPE Offline Bundle for ESXi 6.5' on the support.hpe.com website: https://support.hpe.com/hpsc/swd/public/detail?swItemId=MTX_74b3b76cee654325bfd6f2c674&swEnvOid=4234#tab1

Which one do I need to use to update our ESXi hosts? Both show the same release date but the zip I downloaded from VMware is MUCH larger than the zip I downloaded from support.hpe.com.

What is the difference between those two zips on those two sites?

Your link for the HPE Offline Bundle for ESXi 6.5 tells you what it contains. It's drivers and similiar utilities from HPE, it's not any VMWare ESXi software at all.

The VMware site link is for an ESXi image bundled with those drivers, which would easily explain why it's a lot bigger.