Although the spirit of pilot episode of PGSM and the Anime are similar, it sets the stage for a very different Usagi in each medium. Usagi in PGSM is naive and extremely friendly, but she is also learning on the job and thoughtful. In the anime, Usagi is also a non-traditional heroine, a crybaby and klutzy. She is also overwhelmed at being Sailor Moon, yet grows into it a lot more slowly. I would assume Usagi ends up at a similar place in terms of development, but initially the characters are very different.
PGSM Usagi is shown with black hair that changes color when she transforms. (It is a detail I really like and hope the PGSM Crystal keeps.) But more than that, when she transforms into Sailor Moon, she is more competent as a warrior - perhaps running a bit on autopilot, but she is fighting nonetheless.
In the Anime, Usagi has blonde hair all throughout. When she transforms, she is all elbows and knees in battle. She also starts to wail (which sets off sonic waves), something that is excluded from PGSM.
PGSM Usagi is late for school, trips when going down the starts (not shown), and is asking for food, but those aren’t central. We can imagine ourselves doing silly things like that when late. She even uses her disguise cell-phone to goof off. The entire mission is over her head, but when she hears Naru screaming for help and human cost factors in, she bolts to the rescue.
Anime Usagi is also late and clumsy, but that is how we see her throughout the episode. It also chooses to focus on her poor grades. She puts off going home to avoid getting scolded. She takes a nap when Luna confronts her.
It seems that the Anime was targeted for younger audiences, given all the slapstick humor. Usagi is also portrayed as an immature fourteen year old. In the PGSM, I am assuming the intended audience is slightly older. It seems that the writers want Usagi to be an unexpected heroine with quirks, but relatable and not too over the top.
I think another benefit PGSM had over the anime was that it was not be produced concurrently as the Manga. The writers had a chance to see the story in its entirety before committing to Usagi’s character. It took 200 episodes for Usagi to come full circle. Whereas the pacing of the plot in PGSM more closely mirrors the Manga.
By episode 7, we have Usagi more proficient in hand-to-hand combat, coordinating attacks with the Senshi, and even investigating leads to discovering Tuxedo Kamen’s identity. She acknowledges that she may have deeper feelings for Tuxedo Kamen and chooses not to see him as an enemy, despite Sailor V’s warnings. PGSM de-emphasizes the behaviors that are slapstick humor for children. For example, Usagi pouts or wines(but no wailing). PGSM Usagi always talk about her friendships constantly and is trying to bring all the others together. That element is less present in the Anime. The Anime relies a lot on circumstances. Not that it isn’t there in the live action show, but they do make the those moments more interesting.