Light and clarity
Standard clear glass has a slight green tint at the edges, most visible on thicker panels and on long edges seen against a strong light source. In a north-facing bathroom with weaker natural light, low-iron glass reads noticeably brighter; the absence of edge tint matters more when there's less light to wash it out. In a sunny south-facing bathroom, standard clear is usually fine and the upgrade to low-iron buys less visible difference.