The new Office 365 Service Descriptions can be easy accessed in your favorite browser; just type office365sd.com and you'll get a full list of service descriptions.
Each service description will give you tables comparing features across plans, making it easier to pick the plan that suits your needs the best. To provide an easy, visual overview I've compiled the below table comparing Exchange Online, SharePoint Online and Lync Online across the P, M, and E plans.
In the table I'm using these abbriviations for the plans
- P1 = Office 365 Small Business
- P2 = Office 365 Small Business Premium
(Designed for 1-10 users, maximum of 25 users)
- M = Office 365 Midsize Business
(Designed for 11-250 users, maximum of 300 users)
- E1 = Office 365 Enterprise E1
- E3 = Office 365 Enterprise E3
- E4 = Office 365 Enterprise E4
- K = Office 365 Enterprise K1 (aka Kiosk)
(Designed for 250+ users, no limit to number of users)