So how does the director's cut change the movie?
It drags it out far too long and the tempo falters. The 119 min version is perhaps about 10mins too long as well.
Spielberg needed to whiz from sequence to sequence and he needed to trim the Aykroyd and co sequences even more in the theatrical cut. These are extended in the director's cut which don't add anything of value and even the Matheson/Allen flying sequence goes on far too long.
There is one sequence that was poorly cut out though and that is the Slim Pickens kidnap sequence. The director's cut takes it a bit too far and the theatrical cut makes his kidnap jarring by not showing anything at all, he's just seen driving down the road, the Japanese are on the shore and then he's suddenly aboard the sub with his oversize clock.
Norman! What did you put in my tea?

Thanks a lot for your answer.
"Batter up, bitch boy." -Steve Klaszky

For several years in the States, the only version available was the Director's Cut which lasts about 2:25. If you're a fan of John Candy or Slim Pickens, there are more scenes with them. The theatrical cut you possess is tighter, but I prefer the director's cut. The American BluRay contains both versions and it was interesting to compare them.