Windows Embedded 8.1 Industry is a combination of a normal Windows 8.1 build plus the addition of additional Embedded features you can enable during build/post build. From an application compatibility standpoint it is identical to Windows 8.1.
This is in sharp contrast to Windows Embedded Standard 7/8, where you can omit components from the final build and impact application compatibility pretty easily in a negative fashion.
You can evaluate it with MSDN. I think you have to buy it from one of a few companies, I would contact one of the listed partners: https://www.microsoft.com/windowsembedded/en-us/partners.aspx#none