What do the messages mean when importing a Home Groups CSV file?

When you attempt to import an XML file into Accelerus Light, you will see message relating to the data being imported.  Here is a list of the most common:

Home groups where home group teacher 1 varies

Home groups where there are two (or multiple) variations

Home groups that will be deleted, ie those that are in semester 2 but not in semester 1

Home groups that will be created, ie these are in semester 1 but not in semester 2