Custom Attribute "Resource" versus "Resource Type"?

[rselzler3]

The admin page > Custom Attributes, has both a "Resource" and "Resource Type" variation.   Why are they distinguished and what is the best practice for using them?

Also, on the admin > Resource page, there is a "Resource Type" (just below the "Schedule" descriptor).  Clicking it shows an empty drop down list.  The list is always empty and I haven't found a way to use it.  Creating a "Custom Attribute" for "Resource Type" did not seem to have any effect.  What am I missing?

[nwpro]

Application Management, Resources
Choose Resource Types from the three dots menu
Create Resource Types

What you enter in will now appear in the Resource Type list just below the Schedule descriptor.