What you do not get in ChromiumOS (last time I checked):

- support for flash movies

- support of certain video codecs

- support of sound hardware of many recent Chromebook models

- support of CJK input (at least in Guest Mode)

- support of Android apps

- support of Linux virtual machine subsystem

- support of certain Google APIs (but that is OK for me)

Lack of stable support of CJK input in guest mode (and the difficulty to find anyone capable of solving this problem or supporting us) was the biggest issue for me.

Some years ago, the difference was:

- support for flash movies

- support of certain video codecs

- support of certain Google APIs (but that is OK for me)

which was fine to me.

Note: I wrote the article on /e/ for Desktop