If your Workspace is using the Story Worfklows feature, when you create a Space, it will connect to the Story Workflow you created it in by default. Any time you select that Space, it will switch you to that Story Workflow and show you the filtered stories for that Story Workflow only.
For example, if you create a Space while in the Product Development Story Workflow, it will automatically connect to it, and clicking on that Space will always switch you to viewing filtered Stories within the Product Development.
If you wish to connect or disconnect them from a Story Workflow, you can do so in the Saved Space's menu, under More Actions.
Any time you create a Space (and choose to disconnect it from its Story Workflow), it will just surface Stories that meet the Space's filters you have set in the Story Workflow you're currently viewing.