Choosing between a team site and a communication site should start with your intent and desired business outcomes. Though there are nuances to explore, at the most basic, think about these two use cases:
Create a team site for each discrete group of people or unit of work.
If you are a long-time user of SharePoint, you might be thinking that "team site equals sub-site." Resist the temptation to create team sites as sub-sites! Many governance decisions (for example, the ability to share content outside the organization and who has permission to invite new members to the team) are scoped to the site collection. For the most flexibility both today and in the future, each team should get their own site collection – which is exactly what happens when you create an Microsoft 365 Group or a team site from the SharePoint start page, assuming that your organization has enabled "self-service" site creation. When you provision a new Microsoft Teams or team site in Microsoft 365, you will get a new site collection in your tenant.
If you are doing this right, you will have a lot of team sites. Why? Because you have a lot of projects and work teams – and each one of your projects or work teams will likely have different access and information management requirements. Even if the same work team works on lots of projects, you should still provision a unique team site for each unique project.
Collaborating with people outside the organization? Create a team site for each customer or partner.
Keeping in mind that many governance and security boundaries are scoped to the site collection, create a new team site for each of your different customers or partners if you have an extranet environment. This will ensure that Customer or Partner A doesn't accidentally "see" any content or information from Customer or Partner B. By default, team sites are enabled with external sharing turned on. This can be changed by the SharePoint administrator in the Admin Center.
Each member has the same permissions.
While your team site will have one or more Owners, typically every Member of the team has the same privileges in the site.
The SharePoint start page brings your team sites together
Don't panic about how your users will possibly keep track of all of these team sites – because the SharePoint start page has got your back!
The SharePoint start page in Microsoft 365 brings together, for each individual person, news from all of the team sites in which they are a member (and sites they are following), sites they visit frequently, and other news suggested by the Microsoft Graph. It also shows the most recent activity in the sites each person visits frequently.
Examples of team site scenarios.
Create a communication site to showcase, share, or tell a story.
Here's a way to think about the difference between a team site and a communication site. A team site is where the sausage is made – it's behind the counter and typically private. A communication site is where the sausage is sold – where it's visible to all our "customers" and where they come to buy our sausage. Typically, our customers don't want to know how we make the sausage (or how many times we had to edit that document to get it "ready to share"). They just want to get the finished product.
Communication sites have two distinct user personas.
Most often, a communication site has a small number of people with permission to author content and many people who only have permission to read content. Team sites use Microsoft 365 Groups for permissions. Communication sites use SharePoint groups.
Think about your team sites as where you collaborate and your communication sites as where you communicate**.**
As an example, consider your Human Resources (HR) department. Typically, HR will have at least one team site where the members of the HR team can work on defining a new benefits program or crafting the announcement about an organizational restructuring. During the process of creation, the HR team works privately on a team site open just to the members of HR (or individual "friends of HR" who contribute to one or more specific documents). Once all the back and forth about the message or document or program is complete, the HR team is ready to share the information with the rest of the company.
When they are ready to share, the HR team moves the document to or writes the story in a communication site that is open to the entire organization. They use a communication site to share "team to organization" or "organization to employees" information. While in some cases they may solicit feedback on the information shared in their communication site (for example, with comments on the page), the content itself is typically editable only by a small number of authorized users.
Examples of communication site scenarios.