To add to the above... consider how the seeds are distributed. A maple tree creates single or double 'helicopter' seeds, depending on species of maple. The wind catches the seed and they spiral away from the parent tree a short distance. This creates an ever widening stand of maples. Fruit trees, like apples, spread their seeds by the animals that eat the fruit and deposit the seed in a little mound of fertilizer a distance away from the parent tree. In nature, you'll find stands of maples, but fruit trees are scattered.
Trees that rely on bees for pollination have larger blossoms. Trees that rely on wind for pollination produce a high volume of pollen.
Most trees set more fruit/seed than what will develop. Weather conditions will prune the excess. Man will prune fruit trees to leave fewer fruits, but ensuring larger fruits.
I never thought much about the timing of leaf and flower development, but cold weather fruit trees will leaf just as the flower petals begin to fall. Most of the other large flowering trees in our zone will do the same.
