Once you have defined a namespace (as in 'trmn' in your case) in a DE org, you can only have one managed package defined in it, though you can have further unmanaged packages if you wish. A package can only be of one type, managed or unmanaged, not both at once. The docs do not really state why you would want to have multiple packages in a DE org (mutiple unmanaged or one managed and multiple unmanaged), but you can.
What your seeing in your second screenshot is the options shown when you attempt to 'upload' your managed package (the one associated with the 'trmn' namespace). Hence you only see references to the term 'Managed'. If you create another package (which will have to be an unmanaged one), and attempt to upload this you will see a screen like this when clicking the Upload button.
The ISV Force guide is a great reference to managed packages and the process,