What are the differences between The Cayo Perico Heist's normal and hard modes?

If you try to immediately set up another Cayo Perico Heist just after you finish that heist, you’ll get a message that says "Setting up now will set the heist to Hard Mode."

What are the differences between the Normal and Hard Modes? How is the difficulty increased and what are the differences in terms of payout and other rewards? Are there also changes in the ‘intel’ and ‘prep’ parts (aside from the heist finale)?