Galvanized steel roofs have higher durability compared to aluminum roofs. However, when the posts are made of aluminum, the posts of the galvanized steel roof pergola will bear more weight, resulting in a lower snow load capacity.
Additionally, galvanized steel is prone to rust, while aluminum alloy is almost resistant to corrosion, although aluminum alloy tends to be more expensive.
Furthermore, some brands claim to use 100% pure aluminum, but in reality, pure aluminum is very soft and has a much lower load-bearing capacity than aluminum alloy.