What is the difference between a 7075 T73511 extruded aluminum alloy shape and the same shape in a 7075-T6511?

The T6 or T7 is the temper number, T6 would be less hard but more flexible T7 would be harder but more brittle.

Is that what you were wondering?

Actually I was curious about the numbers following the T6/T7. I do know the numbers represent extruded shapes but what else do they mean?