"Another way of thinking about them is to start with a major scale such as D. If you go from the second note up to the second note (E to E) then that's the Dorian mode of D. It sounds like an E minor but isn't quite because it has a C# in it - that doesn't matter much because the E minor chord will work (E, G, B)."

This is something that's always confused me about modes. When I was taught them, they were explained as above. Later, it was clarified (whether correctly or not -- that's the point of my inquiry here) That, though the above correlation between the Key of D and the Dorian mode described above is that they contain the same notes, that, in fact, the dorian scale from E to E is the E dorian scale (not the D dorian scale as asserted above).

Eh?