So we use Office 2010 and purchase it through volume licensing. I had ordered academic licensing of Professional for my library. Due to some hiccup when I went to retrieve the keys at the computer so I could install it I realized they weren't available. I had already hauled away the other computer so I couldn't return it and she needed office.
I had an extra non academic 2010 Professional license so installed it and put in the key. A Week later I got the academic licensing and product and it appeared I could use the same media install. So I went into office and just changed the key to the academic key and it took it and remained activated.
This is nice and saved me lots of time. Also my portable drive doesn't have to store an additional install folder for office 2010. So the only differences in the two is the license keys you are issued. Nice.