Each application serves a distinct purpose

Microsoft Word: a word processor

Microsoft Excel: a spreadsheet editor

Microsoft PowerPoint: a presentation program used to create slideshows composed of text, graphics, and other objects, which can be displayed on-screen and shown by the presenter or printed out on transparencies or slides.

Microsoft Outlook: a personal information manager

Microsoft OneNote: a note-taking program that gathers handwritten or typed notes, drawings, screen clippings and audio commentaries. Notes can be shared with other OneNote users over the Internet or a network.
Microsoft Publisher: a desktop publishing app for Windows mostly used for designing brochures, labels, calendars, greeting cards, business cards, newsletters, web site, and postcards.

Microsoft Access: a database management system for Windows that combines the relational Microsoft Jet Database Engine with a graphical user interface and software development tools. Microsoft Access stores data in its own format based on the Access Jet Database Engine.

Microsoft Project: a project management app for Windows to keep track of events and to create network charts and Gantt charts.

Microsoft Visio: a diagram and flowcharting app for Windows not bundled in any Office suite.