How are their earthly lives, or their afterlife, different to anyone else’s?
Only their earthly lives are different. Not their afterlife.
Your beliefs effect this life, not the afterlife.
What is true of everyone, is true to Christians. That's the only difference.
Everyone is in the creator (Christ), and the creator is in them. Irrespective of beliefs.
Aligning with this reality brings about the best earthly life, for you, those around you and creation.
Operating in this way, out of spirit, not physical perceptions, is what Jesus did.
If anyone does that, knowinlgy or not, they are “jesus-ing” being like Jesus, who was being a prototype for humanity.
Both Christians and non-Christians can do Jesus-ing or be Jesus-like.
Christians, who get this, are only different in that they profess to know, what’s making them that way, and can tap into it with more understanding, healing, peace & joy (for them) and love, patience, kindness, gentleness and self-control (flowing through them).
Which means when they lose the above, on a given day, they know how to get it back.
It doesn’t make them any better than anyone else.
You might even say they’re cheating at getting the best life.
Being bodyless somewhere isn’t permanent, the bible says everyone will return to a new body in a new combined heaven and earth. Heaven is not an eternal destination, but a present parallel reality that God has empowered only humans to bring to earth, and a "place outside of time” that those whose bodies have died already, are waiting in, for the generation that completes this task enough for Jesus to return and see what a great job we did. He's not coming back to fix creation, He's cheering us on to, having empowered us to as new creations.