"Features that communicate with Google made available through the compilation of code in Chromium are subject to the Google Privacy Policy."

from https://www.chromium.org/Home/chromium-privacy

Any idea what specifically they are referring to?

There is at least some "communication with Google" that could be considered innocuous. For example - accessing their Safe Browsing API (also used by Safari and Firefox).

Probably signing in with your Google Account on Chromium.

One reason I have to use Chrome (over Chromium) is so I can use Netflix due to DRM plugin required: https://bugs.launchpad.net/ubuntu/+source/chromium-browser/+...

Otherwise I agree, Chromium is faster and has less suprises

I use Netflix in Chromium via chromium-widevine (in the AUR if you use Arch.)

What are the practical differences? (Most of my searches come up with 2014ish stuff..)