Chrome vs Chromium

What exactly are the differences between Chrome and Chromium? I use Chromium on Linux because reason ( I honestly dont't know why) however on Windows I use Chrome on Windows which one is better/how exactly are they diifferent?

Chrome is chromium plus some proprietary stuff such as flash, proprietary codecs and google updater (which isn't necessary on Linux since updates are handled by the package manager).

That helped. Thanks for clearing that up

Also as a side note, Chromium is also availeble for windows now days.
I use Chromium on Windows as a replacement for Chrome.