SharePoint can refer to one or more products from the Microsoft SharePoint family.
- SharePoint Foundation: This was the underlying technology for all SharePoint sites and is no longer available for SharePoint 2016
- SharePoint Server: This is the on-premises version of SharePoint. You can deploy one or more SharePoint servers. It offers additional features over SharePoint Foundation, such as BI capabilities, Enterprise Content Management and more
- SharePoint Online: Cloud-based version of SharePoint. The customer does not need to care about the server infrastructure or scalability.
Office 365 is a separate Microsoft offering that includes the SharePoint Online service, although not all plans support all SharePoint features.
The following links provide extensive feature comparisons between available SharePoint versions:
- SharePoint 2013 on-premises vs. SharePoint 2016 on-premises: Feature availability across SharePoint on-premises plans
- SharePoint Features in Office 365: Feature availability across SharePoint plans
- SharePoint Features in SharePoint Online (without Office 365): Feature availability across SharePoint standalone plans
- Merged comparison of features between SharePoint 2013 and SharePoint Online: http://www.buckleyplanet.com/2014/06/sharepoint-online-vs-onprem-feature-comparison.html