SharePoint sites vs. Site Collections - CONFUSED!

There are some great responses, to what has always been a difficult question.  Sites vs. Site Collections will depend on the use, the volume of data and security/admin required and there is no one formula that can be applied to give you your result.

However, that being said, here are a couple of things that I look at when I am trying to design a SharePoint site structure:

1. Security - Does this site need security that is different from the rest of the content on your site, if yes consider that a site collection 

2. Administration - Are you going to be using different Admins to the rest of the site to look after content, maintain security or metadata as it is different to the rest of the site,  if yes, then consider a Site Collection

3. Large Volumes of Content - Another factor that needs to be taken into account is the volume of content that is going to be worked through the site.  As you get larger volumes of content, it requires more structure (i.e. sites), more permissions, more governance and metadata.  While Office 365 is a great system there are also limits,  so if your looking volumes of content say greater than 100gb then consider the use of a site collection over a subsite to help define and maintain your site over the long-term.

On the flip side if your using site collections to help separate and govern your site. you need to take into account your navigation, how you're going to maintain metadata or templates between each site or how search will need to be configured.  Site Collections bring a lot of advantages to larger sites, but they also need more planning to be successful.

I am with you!  How I understand it though, if you create a site collection via the admin center, you are creating a whole new site collection, where sites can be created.  When you go to the Office 365 home page (https://www.office.com/), and create a site, you are creating a site within the existing site collection created by the admin.  However, like I stated before, I am a little shaky myself.  Someone just created a new teamsite for one of our departments, and it was created under the original root collection.  

Hopefully, I made some sense.

Paul

Hi Oz,

If i may offer some personal experience which may help.

I have for the past year been installing/developing SPO for my organization.

1) Adding sites/collections from the admin centre for a Top Level site, this gives good foundation for permissions management which is, imo, up there as a top priority.

2) Sharegate (as mentioned by Dean_Gross) is a really good tool, which gives great fluidity to your environment structure. I have ahd to restructure an SP2010 environment as my first SP experience, and Shargate made the job very comfortable. It also supports many forms of reporting and migration.

3) From a 'Sharepoint Freshy' point of view, having a site/project purpose clear (ours is collaboration due to the nature of the business), and sticking to it is crucial. MS provide so many solutions for so many situations.

Finally, i prefer to have a URL structure /sites/region/dept so that there is an order to the chaos. When you create a site via the Sharepoint Tile, its added to the root by default, so unless you are creating a subsite (and then the URL is beneath the upper site), you will need to migrate the site. OR a Top level site is required, from the Admin centre.

New to the forums and advanced dev of SP, but hopefully the above is of some benefit.

An important point to keep in mind is that External Sharing is enabled/disabled at the Site Collection level. For this reason, I typically recommend that new site collections be created for projects that will require collaboration with external organizations. Give that you may want/need to ensure that external partners do not interact with one another, then having separate site collections makes this much easier. 

But as the others have stated, it really depends on the specific business/industry/requirements. In your scenario I would expect to create many site collections (possibly one for each project or one for each external partner.

FYI, when you create a new Team (in the Teams app), you will get a new site collection in the tenant.sharepoint.com/teams/.... path. A new Folder will be created in the default Documents library for each channel added to the Team. This site collection will not have external sharing enabled.

I think the best answer is "it depends," but this might help.How to Choose between a Team Site and a Communications Site. Yes, when you see "create site" you are actually creating a new site collection - and this is actually what you want for your collaboration spaces. You will have lots of site collections backed by Office 365 Groups for membership when you create Team Sites. (Using Create Site from SharePoint home is probably the easiest way to do this.) When you create a privae team site, you'll want to be sure to assign someone to be the Owner other than you so that they can add other members to the site, both internal and external people as needed. It looks like your questions are about a combination of "broadcast/publishing sites" and private team sites. For department sites that serve as your intranet, you now have two choices - create a "classic" site collection from the Admin center or create independent modern Communication Sites from SharePoint home. Communication Sites should not really have subsites - though they are not blocked in the UI. However, you will currently need to write some code to create a shared navigation for these independent site collections if you want to connect them to feel like a traditional intranet. If you choose to create department sites using a classic SharePoint site collection at the "root," you can create sub-sites with unique permissions for each department. Most of the time, this type of site collection has read permissions for the entire organization and unique edit/owner privileges for each department.

I'm not sure what to recommend for your Operations and Associates sites since I don't know if you are talking about collaboration spaces or communications spaces, but your Project sites should almost certainly each be modern independent site collections created from SharePoint home. That will allow you the most flexibility and security in terms of governing who can have access to each one.