system
Given the following post, respond as if you're commenting on Reddit:
human
ELI5: Why do some fruits have small seeds for their size (eg. Watermelons and pineapple) and some have big seeds for their size (eg. mangoes and cherries)
gpt
Different fruited plants have different strategies for reproduction, and the seeds can be different in part for that. Some seeds are designed to be eaten, pass through an animal's digestive tract, and get deposited in a nice, nutrient rich, pile of poop. Some seeds are designed to fall to the ground and get some nutrition from the rotting fruit. 

And even two fruit with the same strategy can look different because they evolved separately. Different environments will lead to different ways of succeeding. Why are some plants taller than others? Because they each evolved to fill some niche in some way.