People use Microsoft 365 and Office 365 as if they were two products to choose between. For most small and medium businesses they are not. The confusion comes from a rename and from how the licences are now bought and committed, not from a real fork in the software.
The rename
In 2020 Microsoft renamed most of its Office 365 business plans to Microsoft 365. Office 365 Business Premium became Microsoft 365 Business Standard, and so on. A few Office 365 plans still exist by name at the enterprise level, such as Office 365 E1, E3, and E5. So on an SME invoice, Microsoft 365 is usually just the current name for what used to be called Office 365. The apps, Word, Excel, Outlook, Teams, SharePoint, are the same.
What CSP means
CSP stands for Cloud Solution Provider. It is the channel you buy the licences through. You can buy Microsoft licences directly from Microsoft on a card in dollars, or through a CSP partner. Through a partner you get one local invoice in your own currency, a single point of contact for licensing and support, and someone in your timezone to call. The licence itself is identical. What changes is the buying and support relationship around it.
The New Commerce Experience, and why the term matters
This is the part that trips people up. Under the New Commerce Experience, the term of a subscription is separate from how often you pay for it. An annual term is a twelve month commitment even when you are billed monthly. The monthly billing is a convenience, not a monthly contract.
The practical consequences:
- You can cancel or reduce seats only within seven calendar days of purchase or renewal. After that window the seat count is committed for the rest of the term.
- You can add seats at any time. It is only reductions that are fixed.
- A monthly term exists too, at a higher per-seat price, if you genuinely need the flexibility to drop seats each month.
None of this is a partner rule. It is how Microsoft structures the New Commerce Experience. A good partner just makes sure you choose the term deliberately rather than discovering the commitment later.
Which plan for a small business
For most SMEs the choice is between the Business plans rather than the enterprise ones. Business Basic covers web and mobile apps with Teams, Exchange, and SharePoint. Business Standard adds the desktop apps. Business Premium adds device management and security on top. The right answer depends on whether your team needs installed desktop apps and how much security tooling you want to run yourself. That is a short conversation, not a spreadsheet.
The takeaway
The software is the same whether the invoice says Office 365 or Microsoft 365. The decisions that actually matter are the term you commit to and who supports you. If you want that handled locally, in PHP, with the commitment explained before you sign rather than after, that is what a CSP partner is for.