Blocks

Sure. Assuming your default role is 'Authenticated user', turn editing on and click the roles icon on the block that you want shown only to logged in users. Select the Override roles tab and choose the Guest role. Set the View block capability to Prevent. Now only logged in users will see that block. If you want a block to show only to non-logged in users, override the Authenticated user role on that block and set View block to prevent.