I've been wondering the exact same thing.  I bought a refurbished computer with massive amounts (for me) of RAM and a 1Tb HD, but it's got Windows 7 Business on it, while my main machine is an eMachine with 2Gb of RAM and Windows 7 Home.  I've been trying to get everything moved to the refurb but I keep getting "you can't do that because it's different versions" song and dance.  If we are all going to Windows 10, what difference does it make?