Πριν plus a length of time means ago and points at a finished moment: πριν από δύο χρόνια. Εδώ και plus the same phrase means for that long and describes something still true. Από plus a date means since.
Examples
- Πριν από δύο χρόνια ζούσα στη Θεσσαλονίκη.
- Two years ago I was living in Thessaloniki.
- Μένω εδώ εδώ και τρία χρόνια.
- I have been living here for three years.
- Όταν ήμουν μικρός, πήγαινα στο χωριό.
- When I was small, I used to go to the village.
The mistake to avoid
Πριν is ago; εδώ και describes something that is still going on.
Where this fits in
Το παρελθόν και το περασμένο Σαββατοκύριακο, Greek A2: Talk about the past: yesterday, last weekend, and travel memories.