Workspaces are where you build and host sites.
Workspaces define the billing entity- everything is charged to the workspace owner, including all hosting fees for any hosted sites in that workspace.
In Webflow, all sites - hosted or un-hosted - must be connected to a Workspace.
Your Workspace plan determines your development capabilities- primarily the number of sites you can be developing at one time, and the capabilities you have on those un-hosted sites, e.g.;
The Workspace plan only affects your capabilities on unhosted sites. If you have hosted sites in the workspace, their capabilities are determined entirely by their site plan**.
** The one exception to this is site export, which is entirely a Workspace plan capability.
Site plans define a site's capabilities one it has been hosted. All paid sites plans come with;
Specific site plans can add other capabilities;
Both Workspace and Site plans have a free "Starter" plan. If you are a freelancer or agency, make certain to check out those specific plans.
For Example, look at the Custom Code feature. If you need Custom Code, you can either get a PAID Workspace plan, or a PAID Site plan. Either will work.
The same is true for getting the 150 static pages.
Basically, you can think of FREE Webflow ( paying $0 ) as a taster. You can try most anything, except custom code and code export.