Hi, Im a bit confused with the airport set up?

As i understand it there's two?

One is called Don Maung and the other Suvarnabhumi.

Which is the old one and which is the new one?

Im looking to book my flight soon.

My mate is flying i into Suvarnabhumi.

Im gonna fly the same day as him but cant get on his flights so we will meet up at a hotel.