The Standard Access Pass just gets you the levels from the base Hitman 2 game (Hawke’s Bay-Isle of Sgail). The Gold Edition gives you that plus the Expansion Pass content. (New York, Haven, the two Sniper Maps, etc…)
And they’ve said in the Known Issues thread that the issue with getting Steam users the levels they already own should be resolved by the end of the month at the latest:
Whilst we’ve been busy launching HITMAN 3, we’ve also been working on the promised solution for allowing PC players to import locations that they already own into HITMAN 3 on Epic. We’ve got that solution worked out and it’s currently being tested and verified from all angles to make it as robust as possible. In terms of timing, it’s definitely a case of sooner rather than later. Even with the longest estimates we’ve looked at, the solution will be fully rolled out before the end of February. We’ll keep you updated with the next steps.