) for only a few weeks, I can definitely see differences between the two.The paler one is very shy and inquisitive. Whenever I rearrange something in the tank, it's her job to take a few laps around the tank and stare at everything (to make a mental map, maybe?). Shes the one currently fascinated by the heater. She also prefers getting her food directly out of the little worm-cone feeder thing, which I tilt to the side so some bloodworms fly around the tank while others stay inside.
The more yellow of the two is pretty aggressive! She's the one who enjoys chasing the bloodworms around the tank. She also likes following my pencil eraser when I hold it up to the tank... she'll come running over to follow it! The other one will sit back and stare from afar, still paying attention though not as engaged.
If I hold my face up to the tank, they both like to come and greet me.
They also like to glass-pace in a certain spot near me when I'm studying... I think they're jealous of my calculus work because I'm paying too much attention to it!
What about your puffers?
shes been doing this for a few days now, after shes been fed she will bury herself and looks to me shes eyeballing me as to tell me i can go back to sleep now 
..she seriously has me wrapped round her fins..but because she is cute and she makes me laugh i dont really mind.
