Excel Power BI
Power BI Desktop
The differences between the two are purely cosmetic.
Anything you build in Excel PBI can be converted into PBI Desktop with one click – because they use the same engines and languages! (Some of the visuals might not translate over, but those are quick to recreate. It’s the brains of your models that are important, and those transfer effortlessly.)
CREATE with Power BI Desktop
Power BI Desktop is where you CREATE models and dashboards.
SHARE with PowerBI.com
PowerBI.com is where you PUBLISH and SHARE share those models and dashboards. Then, others can view and interact with those dashboards in their browsers and, even better, on their mobile devices.
The answer is the SAME for Excel PBI vs. PowerBI.com – you BUILD in Excel, and PUBLISH to PowerBI.com. Your visuals will still be Excel visuals – pivots and Power View, for instance – but WILL be useable in a browser (and also on tablets to an extent, but not on phones).
But with Excel PBI, you also have the option of “on premises” SharePoint as your publishing platform, so if you’re not ready for the cloud, this might be the right path for you.
What is Power Pivot?
Explains why Excel PBI is such a life-changer over traditional Excel alone. (Yes, it’s written from the Excel PBI perspective, but it still explains the original and most central of the PBI Engines – the DAX formula and modeling engine – in a manner that’s relevant to PBI Desktop.)
Transitioning from Excel PBI to PBI Desktop
Drills down on the similarities between the two environments. For more on the strategic reasons why Microsoft has two environments, see What is Microsoft Up To?