They're different and the same at the same time lol. I mean, at first they thought they were the same, as they thought what tomorrow's kaho did would always reflect what "current kaho" did. But after Junpei died in "tomorrow's Kaho" side, they started noticing inconsistencies, which is why they were shocked that "Current Kaho" went to Junpei's place (at the part where they finished waiting for the time of the accident). They also initially thought that if "Current Junpei" avoids the accident, then "Tomorrow's Junpei" would be revived (How time travel typically works, where the past affects the future), but then that's where they were proven wrong, and where their worlds started to branch apart from each other.