Well the name is just the different
xD. JK .
Actually Jacob is right, SRWare Iron is Google Chrome with custom GUI, spyware/tracking removed, and a little bit faster. It even has its own add-ons. I prefer SRWare over Chrome.
Chrome = Webbrowser
Chromium = Webbrowser as an operating system
I use SRWare Iron Chromium, because of its different specs.