MS office version 7 or 10

Office 10?
Office 2010 is version 14 I believe.

Of all the Office version I use I always go back to office 2010 even though it's 8 yrs old now.
It seems to have the least bugs.

Do you mean Windows 10? Office versions are usually referred to by their year of release. The latest is currently Office 2016.
(All versions also have a "Build Number" that looks like this: 8730.2127)

Google will tell you what has changed, there is too much to list here. MS has made a habbit of now posting whats changed/new features to make this easy to determine.

For example, article titled "Whats new in Excel 2010":

https://support.office.com/en-us/art...b-d003e4a2b329