Differences of duck turkey and quail?

Considering all species - nothing consistent. As European man travelled the world, discovering new birds, he named different birds quail and partridge with no knowledge of what they really were. Stone partridge from Africa are smaller than a California quail, Grey/Hungarian partridge are actually pheasants, N American quail are nothing like as related to AAsian quail as are African Francolin. As with so many birds, common names are very useful but meaningless in terms of what the bird is in evolutionary/systematic terms.