IGR-AEP is on LAN Airlines
AEP-FTE is on Aerolineas Argentinas

We're not flying out of EZE. We're landing in AEP, picking up our bags, checking in at the Aerolineas counter (ideally), and then venturing our in the city for the first time.

We have only a few hours in the city to have lunch and walk around, but we will be back to visit Buenos Aires for a longer period of time at the end of our trip.