OK so chromium is like a foundation upon which a bunch of other browsers have been built. Its FOSS, but yes, it is headed up by Google, and it uses a lot of Google junk, from what little I know.
Degoogled Chromium is exactly what it says on the tin
Vanadium is chromium that, in GOS's pursuit of being FOSS and very secure, is also, by necessity, "degoogled." I don't know if they pulled from Degoogled Chromium or if they built it from base chromium, but I dont think it would be inaccurate to consider Vanadium as, from a nontechnical standpoint, to basically be a security-hardened alternative to Degoogled Chromium.