Rob Griffiths (MacWorld, macOSXHints) explains the difference 
between white and blue folders in Mail.app in a post at MacWorld.
In a nutshell, blue folders are mailboxes and white ones are not:
The two green-highlighted entries correspond to the two white folders in the leftmost image. Notice that neither folder has the .mbox extension. The blue folders, on the other hand, do have the extension, and can be used to store both messages and folders—they are true mailbox folders.
Rob goes on to suggest why you might want white folders and how to create them the easy way and the hard way.
[Thanks, Chin]
uh, so another question – how does one move all the crap under ‘import’ back up a level? through finder and dragging them manually? any other way?