I played to level 6 on classic, then restarted on tactician. Now at level 10. I feel like on tactician they have access to more skills and seem to know who my weak characters are.
Best way to know is to check the Kickstarter vids, I know some of them they explained their reasoning in developing the game difficulties. I don't remember where I read it but they explained that this is pretty much the final version of the game. They will fix bugs, glaringly obvious issues, and continue mod support. Other than that, the game is as they intended.
I could definitely tell a difference, and not just in hit points. But I could be wrong.