place your cursor over the arrows...tooltips for the architectural select will be: 'select objects', for the CAD select: 'select CAD objects'
or look at the status bar on the bottom of the window
on the status bar, the architectural select arrow displays as:select any object for moving, resizing, or deleting
the CAD select arrow displays: click on a CAD object to selct it for moving, resizing, or deleting
or...in the customize toolbar dbx when you mouse over the tools, the button description is on the right side of the dialog...
I do not even use the two different modes , as I have customized my toolbars using the 'all views' setting...so the same toolbars with the same tools are in the same locations, in all views, and I have the CAD tools on their own toolbars, so i do not use F2 (architectural/CAD toggle) at all...
here are some other threads on the selet tool in v10, pay attention tot the snap distance settings
http://www.chieftalk.com/showthread.php?t=11879
http://www.chieftalk.com/showthread.php?t=12207
http://www.chieftalk.com/showthread.php?t=12273
http://www.chieftalk.com/showthread.php?t=16108
....also in the wall defaults, you might try a lower value for the wall snap distance...(mine is set to 5½"( about 140mm))