It's hard to say for sure. Deku has grown a lot, but All For One is a powerful villain. It depends on various factors like their current abilities and the circumstances of the battle.
If Deku had One For All early, it could either make him a hero sooner or cause him more problems. It might make his enemies step up their game or force him to face even greater threats. It's a fascinating what-if scenario that could go in many different directions.
Naruto's outgoing and boisterous personality would make Deku more confident. He would probably be more upfront and less shy. Naruto's strong sense of justice would also intensify Deku's already existing desire to help others.
The main differences are in their expressions and some minor details of personality. In the manga, Deku might seem a bit more intense, while in the anime, he's sometimes presented a bit softer.
Well, obviously Deku in two forms - the younger and the older version are the main characters. The younger Deku is the one who is still growing and learning, while the older Deku has more experience.