No they aren't actually different. Here is what happened.
Google just this week announced and released a brand new version of its Maps app that looks quite a bit different. Your girlfriend, or you, probably has the new version while the other does not. Google said the update is rolling out slowly, so it should appear for you in the Google Play Store within the next week or so. Not everyone has it yet. Example, right now I have the new vesion on my S4, but my dad and girlfriend both still have the older version of the maps. It will come eventually, just gotta be patient.