Papayas come in a wide range of sizes, shapes and flesh colour, all depending on the variety grown, but fruits from a female plant are generally rounder and sweeter than those from a male plant. Papayas have three sexes, female, male and hermaphrodite, (meaning both sexes in one plant). Usually only female and hermaphrodite plants are grown for fruit. Hermaphrodite plants are self fertilizing, while in a plantation of female papayas every fifteenth plant should be male.
A source for quality, disease resistant seedlings is KALRO, Thika in case you want to grow a certain variety and not start from seed.