"change 128 GB SSD for the 256 GB SSD (11" Air)"に関する回答Yes. I have successfully done the swap and there are no issues with the physical size of the drive. Just make sure you have the correct Torx Security size (which is T4 and not T5).
"Are the 2010 MacBook Air 13" and 11" memory cards interchangeable?"に関する回答The short answer, yes they are interchangeable. Both machines are running smoothly with no issues whatsoever.