After just getting of the phone with Client Care and talking with a number of different Adobe Analytics representatives I became aware that there's currently no information available on how mobile devices are classified as Mobile vs. Tablet.
Using the user agent string devices are categorized as either one or the other in the Adobe database, but it is not specified whether or not the breakpoints are established based on screen size and what that size is.
In a time when phablets are becoming more common this information should be available to allow us to answer these questions when they come up.