The core apps thus grow in mission: Excel is a BI tool. Word is a collaborative editorial system for the production of publications. PowerPoint is a media production platform for for live presentations and, increasingly, for delivering more effective presentations online. Outlook is a time and task management system. Access is a rich client front-end for data-driven self-service SharePoint applications. OneNote helps you capture ideas, corral random thoughts in a semi-structured way, and then tie them back to other, more rigidly structured, Office documents.
quite a nice article (h/t @mynewoffice2010)