Download win 10

How do you know when the latest version of windows 10 is available? I have downloaded the ISO with the MCT and it is version 10586.35. It is 3,198,720 MB. I downloaded the ISO from ThchBench. It is 3,922,852 MB. I don't know which version it is. There is 724,132 MB difference.

My guess is they are both the same version and the latest too (as along as the MCT was also freshly downloaded). The reason the sizes are different is because the MCT uses an install.esd compressed file and the Tech Bench ISO uses a install.wim file which is not compressed. The file contents are the same though.