At every passenger exchange there are 200 + 320 = <<200+320=520>>520 different people.
One hour is 60 minutes, so during one hour, a train comes 60 minutes/hour / 5 minutes/train = <<60/5=12>>12 times.
So during one hour, 12 trains * 520 passengers/train = <<12*520=6240>>6240 different passengers step on and off the train.
#### 6240