volgens Stuart Mealor.
As Helen says the target Moodle site version should be the same or higher than the original. However, I have Restored Courses into a slightly earlier version (e.g. 2.2.2 to 2.2.1) and had a warning message, but the restore was OK - just basic documents. With more sophisticated activities it may not work.
The other factor here is that if you have non-standard modules and plugins in the source site this may cause problems during restore if they do not exist in your target site. The way around this is to deselect these activities during the Backup process, or install the same plugins in your target site.
This is always a consideration when using plugins, or indeed a specific distribution of Moodle.