Hi
The main difference is the 1820g has QoS, 8 levels for defined services such as VoIP etc...
Jumbo frames depends upon your need and can slow down normal flow if not suited to large blocks.
We do not use jumbo frames in normal circumstances
A nice feature of procurve switches though, is dual firmware options, albeit the 1810/20 are only semi managed level 2 switches ie webgui only, no cli
Many thanks
John