Microsoft has just announced that effective April 21, 2019 — Office 365 will be formally renamed to Microsoft 365. You can read more about it from Ingram Micro.
Here is a quick list of the name changes:
Office 365 Business Essentials is now Microsoft 365 Business Basic
Office 365 Business Premium is now Microsoft 365 Business Standard
Microsoft 365 Business is now Microsoft 365 Business Premium
Office 365 Business is now Microsoft 365 Apps (for business)
Office 365 ProPlus is now Microsoft 365 Apps (for enterprise)