They're not almost completely different actually. Bare in mind they both stick with the same or similar chord progression. "Fuck Gravity" has a lead in the intro which is exactly the same as the big, main lead in the drop, just low passed. It's kind of hard to hear but it's definitely there. Then it uses a little break fill right before the drop to give some indication of change occuring. Similarly, "A Little More" slowly builds up elements from in the drop using low passes, etc to make it sound nice to our ears because we understand what's about to come of the track. Also using typical build up elements usually indicates there's drop about to happen. I also want to say they obviously stay in key, which makes it easy for listeners and makes it easy to sound natural. Of course you can do key changes but they requires a little more of chord progression manipulation or fills to make it work correctly.
In conclusion, it's about building up elements and creating an anticipation for the next part. Best options for easy, natural transitions, is to keep a chord progression that's the same or similar, mainly starting with the first chord being the main root chord of the key you're working in when the next part begins, maybe slowly introducing a melody line that will be the main focus of a second section.
I hope this helps