Cannabis seeds are created as soon as a male plant has fertilized a female plant with its pollen. The seeds are then visible on the female plant's stem, on the branches and where non-fertilized cannabis plants have their flowers. No flower will emerge, but a kind of forest with seeds. If there is no male plant near the female plant, the female plant will not be fertilized. Unfertilized female cannabis plants grow a flower and do not have balls on the stem and on the branches. A female plant cannot therefore produce offspring, but is limited to producing a flower. The flower is better known as cannabis buds.
When a female cannabis plant has been fertilized by a male plant, this can be recognized by the beginning of the branches on the trunk. This will produce hanging balls (seeds) instead of upward-pointing hairs.
See the illustration below to clearly see the differences.