Like my review of Footloose, this is a classic, everyone has seen it, everyone loves it. It's one of those movies that came from your childhood and lasts well into the adult manboy years.
So, we're going to do a comparison with the remake.
For starters..the Ghostbusters plays it straight. The comedy is presented like a drama and that is usually the absolute best way to do comedy...straight.
And conversely the remake is just sort of over the top. And when comedies try that hard to be comedies, they stop being funny.
Another part would be scene length. And again, playing it straight, the opening of 1984 is short and honestly kind of scary...
...when the remake drags on and deals with characters that honestly have nothing else to do with the film but introduce it. You lose interest sort of fast.
And this can be seen again with the humor. The introduction of the car in the remake is prime example. Pulls up with a hearse, someone makes a joke about checking to see if there is a body in there....
...the scene SHOULD stop when they look at the hearse and cut away to a different scene. But the remake drags on and the joke loses momentum and falls flat when it COULD have been an easy laugh.
Conversely in 1984 you have jokes like the Twinkie that ends with "tell him about the Twinkie" and it is funny because it doesn't drag on in an effort to be funny. The same can be said about testing the proton packs, the joke ends fast enough for it to actually be funny.
And then there is the script and direction, the 1984 version stuck to it and made sure everything was tight, even when it was improvised, it wasn't allowed to get out of control.
But the remake the actors took control and the improvisation went on too long, even with scenes being cut.
So what you have is a tight and fast film that is a comedy played straight like it should be...and one that everyone knows and loves because of it.