Naming Triads: The position that a chord is in does make a difference in how it sounds, but it is a fairly small difference. Listen to a G major chord in different positions.
A much bigger difference in the chords sound comes from the intervals between the root position notes of the chord. For example if the b in one of the above chords were changed to a B flat, you would still have a G triad but the sound would be much different. So chords are named according to the intervals between the notes when the chord is in root position.
The chords above are all G chords but they are four different G chords. The intervals between the notes are different so the chords sound different.
Major and Minor Chords: The most commonly used triads form major and minor chords. All major and minor chords have an interval of a perfect fifth. A perfect fifth is 7 half steps from the root. A perfect fifth contains a major third and a minor third. If the interval between the root and the third is minor, than the chord is a minor chord. If the interval between the root and the third is major, (with a minor third between the third and the fifth) than the chord is a major chord.