When you say "voicings" what do you mean?
When you play a chord, certain notes in the chord have different functions. We refer to the various notes in a chord by their numeric position in the scale that would underlie the chord. For example, let's look at the notes in the C major scale to keep it simple, as there are no sharps or flats:
C D E F G A B C
You can number the scale steps from 1 to 8:
1 2 3 4 5 6 7 8
C D E F G A B C
If we spell out a C major chord, the notes will be:
C, E, G
The C is the 1, E is the 3 and G is the 5.
In a chord, the 1 is the tonic or root of the chord. The 5 is the dominant and while it helps you orient to the key it does not provide any information as to whether the chord is a major or a minor, as this note would be the same either way.
The 3rd is known as a "guide tone," which does give you information about whether the chord is major or minor. If you play the third as we've spelled it here, the chord is a major chord. If you drop the third a half-step, in this case the E becomes an E flat, you'd hear a minor chord.
Now that you know the above, a voicing is an arrangement of a chord that may repeat some notes and leave other notes out. One obvious case is what we call power chords, which have only the 1 and the 5.
In this case, we're leaving out the 3, and the chord becomes ambiguous, being neither major, nor minor. In our current example, if someone is playing a C power chord, you could play the C major scale or the C minor scale over it and it would sound fine.
Voicings may also repeat chord tones. The classic power chord grip on guitar plays the 1, 5 and 1, or in our example, the C, G and C. The repeated 1 is an octave higher than the first one. The chord functions the same within the music, meaning the same scales will works with it, but the sound is a bit richer.
Another possible voicing is one that leaves out the 5. This would leave you playing the 1 and 3, which gives enough musical information to at least imply to the listener that it's a C major chord. A C major scale would sound good over this, but if you played a C minor scale, that flatted 3rd (Eb) would sound like a clam.
The bigger the chord, (meaning the more notes it has, e.g., 7th, 9th) the more numerous the chord voicing possibilities. The rules get a little more complicated in bigger chords as to which specific notes you can leave out and still preserve the quality of the chord, but the underlying concept is the same.