On what basis are plants divided into spore and seed?

Plants are divided into spore and seed according to the structure of their reproductive organs. Initially, all plants were spore. Then, in the process of evolution, seeds began to appear in plants, because this increased their survival in a changing habitat. The advantage of seeds was that they could keep a living embryo for a long time, were more resistant to climatic and temperature fluctuations. Most of the spore plants were not resistant to temperature changes and especially to drought.