When I try to distinguish chords, I follow these steps when practicing.

1. Determine if it is Major, Minor, or Weird ( Weird being either Diminished or Augmented )

2. How many different notes can you hear in the chord? 3, 4, 5...etc.

3. Listen to the bass note and try to hear where its "tendancy" to resolve is...aka the leading tone always sounds like it wants to resolve to tonic. ( this is useful for discerning inversions of chords ).

Hope this helps.