Obi-Wan Kenobi would already be a Jedi Knight when Episode I begins, and Yoda would never appear. Although Kenobi would sometimes brag about his former master in ways that Anakin, and the audience, would suspect as exaggeration. Yoda would be described as reclusive and mysterious, keeping out of the political arena, and hand-picking his students to invite to train on his hermit planet.
Anakin would be a teenager when he meets Kenobi, with the reason he’s reluctant to leave home having to do with his mother’s delicate help or desperate quality of life rather than his being a child. He would already have a relationship with Owen Lars by this point, who could be either a relative or close friend. Owen would be vocal about his disagreement on Anakin leaving, but equally vocal about looking after his mother.
We would get onscreen exposition and/or a flashback about Darth Bane and the line of succession about the rule of two. We’d also get some basic information about why the Sith are bad and why it matters that they may resurface.
The Clone War we see would be only the most recent of multiple clone—related conflicts, and the remaining Jedi would feel that allowing it to begin would be their downfall. The audience would be clued into a line of succession and planning, of which Palpatine is the culmination and continuation. The Clone Wars would be set in motion by the end of Episode I, with Episode II showing us Kenobi and Skywalker fighting together.
Toward the end of Episode III, Padme would travel with Leia on Alderaan and it’d be more convincing than what one can do via fan editing! Anakin’s fall to the dark side would not be predicated on saving her life, and would resemble Lucas’ ideas circa 1983.
3PO would be part of Padme’s ship compliment, and R2 would have been Anakin’s secret project. Not built, but rescued and souped up. Both their memories would be erased at the end of III. Kenobi would maintain a consistently dismissive attitude toward droids and would not place a comforting hand on 3PO on Mustafar, and never referring to either by name. R2 wouldn’t accompany Anakin during the Clone Wars, as Jedi don’t deal with droids at all.
There would be no virgin birth of Anakin. There can still be a prophecy, but it’d be kept controversial among Jedi and up to interpretation.
It would not be uncommon for Jedi to have families, and there would be no celibacy requirement. One may still need to pass tests and train, but if one is capable one can follow in their parent’s footsteps.
When he is struck down, Anakin is aware that he will have a child, and expresses he would give the child his lightsaber one day. He is lead to believe Padme died by his actions, although it’s more like the cherry on top rather than a supreme point of irony.
Jedi outfits would vary a bit more than brown robes.