We use several different resources for our clients. Here is the link to the official service description from Microsoft: TechNet
It can be cumbersome to read, so a SharePoint MVP developed excel version that are significantly easier to sort and work with. http://www.andrewconnell.com/blog/SP2013-and-Office-365-Feature-MatrixAn-Easier-Way-to-View-It
Direct link to management version:
Direct link to the full version:
To compare SharePoint On-Premises vs. SharePoint Online click here: http://products.office.com/en-us/SharePoint/compare-sharepoint-plans
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