The main alloying elements in 7005 aluminum are zinc and magnesium. In 6061 aluminum, you have magnesium and silicon.

This means that while 7005 aluminum extrusion performs excellently on strength and corrosion resistance, 6061 aluminum extrusion is renowned for machinability, weldability, and strength-to-weight ratio. With a higher zinc content, 7005 aluminum extrusion also tends to be stronger and more expensive. The alloy would also give worse results than aluminum 6061 for machinability because of its higher melting point.

7005 aluminum extrusion is usually applicable in high-stress heavy-duty projects while 6061 does a better job in general industries.

Finally, on cost, the likely scenario is where the 7005 aluminum extrusion costs more.