Voicing chords for an arranger keyboard? Voicing chords for piano? They are different.
One is a matter of speed and work-arounds – the other is a matter of spreading the chord over one or two octaves, giving more depth to the sound.

Piano voicing:
C major chord – C E G
C -- is important because it is the root.
E -- is very important because it decides if it is a major or minor chord.
G -- is the least important.

If the melody note is C my left hand plays 1st and 5th C—G. My right hand plays the C and the lower E.
If the melody note is B, left hand plays 1st and 5th –C—G, and my right hand plays B and the lower E. I do not have to repeat the C note.

This as basic as it gets. The problem comes when we want to add (Expand the sound) to 9th, 13th, a minor9th , or a dimished 9th – ect.

The most important notes are the 3rd and the 7th. (not the root) The 3rd decides major or minor, the 7th decides major or dominate. C major 7th is in the C major scale, C dominate 7th (C7th) does not belong to the key of C – it belongs to the key of F.

Color tones – they add color to the original chord. 6th, 9th, 11th 13th. 9th, #9th, sus7th, b5th – ect.

I like following this method because it helps me understand the why’s and how’s, and I can build on what I have learned.
Hope this helps, John C.