Simply put, Harvey performed Edna Turnblad as a real woman and not in the expected drag format. For the original 1988 film version of HAIRSPRAY, John Waters wrote Edna for the legendary Divine who always played his female roles this way: as real woman. This became the foundation for the character and how EVERY actor who has played the role has honored. Also, no actor has ever modified their voices for their Edna to simulate a woman's voice - they used their own, which was a true artistic approach that showcased the talent of the male actor. This continues with Emmy Award winners Louie Anderson playing the role of Christine Baskets on FX's BASKETS even Jeffrey Tambor as a transgender woman on Amazon's TRANSPARENT.
Now, on stage you need to play BIG. You need to play to the balcony. As mentioned above, Harvey is a large personality which glowed on stage. The voice, the line readings, his persona radiated. On TV you need to bring down that big overplaying as TV is an intimate medium - the camera is close to you so you have to be more natural though you can still be animated. Harvey did tone down his persona for TV but his line deliveries were still done for the stage so they seemed unnatural at times. Andrea Martin and Martín Short followed suit and were playing to a Broadway house even with the cameras up close. Kristin was a bit more controlled.
A note regarding performing styles for different mediums: Joey Grey originated the role of the Emcee in the original 1966 Broadway production of CABARET. Won a Tony Award for the role and played it for years. When he was cast for Bob Fosse's 1972 film adaptation he assumed he'd just go in a do his thing as he knew the role inside out. Nope. He has said Bob Fosse explained the difference of performing on stage to performing on film where you will be projected in close-up on a huge silver screen. Joel had to relearn the role and create a whole new version of the Emcee.
Also of note, due to her larger-than-life personality and presence, Carol Channing never made the transition to film. She appeared for a few minutes in the original 1968 film version of THOROUGHLY MODERN MILLIE and earned an Oscar nomination. That's how much she made an impact in the film - for just a few short minutes. Her personality was good enough for a few minutes but she could NEVER hold an entire film with her personality. It was (and is) too much. Sadly, this was why she wasn't in the 1969 film adaptation of HELLO, DOLLY! On stage (as Harvey) she glowed but to have her personality in tight shots carrying an almost 3 hour film? The audience would have a headache in the first 15 minutes. They're like human cartoons.
