Stantz is a very positive person. He's goofy and very motivated to capture ghosts. He's also kind of naive, for example, when they were all looking at a house to buy and he asked if the pole still worked.
Venkmen is more rude and disrespectful in the movie. He shows sarcasm to Stantz and Spengler, but is polite and flirtatious to Dana.
There is also dramatic irony when Venkman did the ESP test and the audience knew he lied about the results but the two people taking the test didn't.
Dana is not as promiscuous or flirty as she is painted out to be in the script. She grabs the attention of many characters in the movie. At first she rejects Venkman profusely but then accepts him later on.
Whenever Venkman, Spengler, and Stantz destroyed the hotel to capture the ghost, Stantz stated, "Now that wasn't so bad was it." This is an understatement because it took alot of effort to catch that ghost.
Venkman is still sarcastic through out the script and flirtatious with Dana, but isn't as rude in the movie.
In the script, Dana is more flattered by Venkman's remarks than offended but still doesn't show interest at the same time. She shows interest as the plot progresses.