For past express editions, I've been able to find a "compare editions" page that shows what features are available in express, professional, ultimate, etc. Something like this.
However, every comparison table I've seen so far omits the express editions. Surely Microsoft must have a list of things you get by upgrading to Visual Studio Professional from an Express Edition--after all, it's a free product, and they would like you to upgrade to a paid product! So, where have they hidden this feature comparison table, or "reasons to upgrade to Professional" list?