Licensing with Office 365 is a bit different than normal on-premises software. With Office 365, rather than purchase a SKU, you subscribe to a Plan. A plan represents a set of services the user of that plan receives. In the early days of Office 365, the plans and the ability to move between them was problematic. If you took out a small business type plan and then wanted to move that subscription up to an Enterprise plan – you couldn't. It was all a bit messy. Then MS did two things: they simplified the plan structure, and enabled you to mix and match with the plans.
The new plan structure for Office 365 contains 6 separate plans:
- Office 365 Business Essentials
- Office 365 Business
- Office 365 Business Premium
- Office 365 Enterprise E1
- Office 365 Pro Plus
- Office 365 Enterprise E3
The Office 365 Business/Pro Plus plans are just the on-Prem fully installed set of Office software products. This includes Word, Excel, PowerPoint, Outlook, Publisher and One note). The Pro Plus plan adds Access. These plans are a way of subscribing to Office, versus outright purchase. These two plans just include the software – there's no on-line services or server software. These plans appeal to organisations that are looking to spread the cost over time. Once nice aspect of these plans is that you can load Office on up to 5 systems (e.g. laptop, desktop, home, etc).
The Business Essentials and Enterprise E1 plans are, in effect, online Office (including the Office Online Apps, plus and Exchange mailbox, file and storage space, plus both SharePoint and Lync. The E1 plan has a few added features appropriate to larger firms, such as compliance, BI and enterprise management of applications.
Finally, the Business Premium and E3 plans are the combination of the first two: full office plus mail, SharePoint, Lync. The E3 plan as above gets a bit more.
For fuller details of precisely what each plan offers, see https://products.office.com/en-gb/business/compare-more-office-365-for-business-plans.
What this now means is that any organisation can mix and match any of the plans. The restriction is that a a given subscription is limited to 300 seats of less of the business plans. So you could give the Business/ProPlus subscription to the road warriors who need off line access, while giving Business Essentials to in-house staff could use Office in the cloud. This offers a lot of flexibility.