What is the difference between 7075 and 6061 aluminum plates?

Answer 1

From the Internet:

The difference is how much of each is contained in each. 6061 aluminum alloy contains less zinc than7075. Meaning that while 6061 alloys provide superior welding abilities and workability, it doesn't boast the same high strength and stress resistance as 7075.

So, depending on the intended use, one would choose one or the other.

Answer 2

Both contain magnesium, copper, iron, silicon, zinc, manganese, titanium, and chromium. The difference is how much of each element is in each one.