What's the difference between pyramus and thisbe and romeo and juliet?

Pyramus and Thisbe, who were neighbors, were planning on eloping, but Romeo and Juliet actually got married. They both had families that didn't like each other. Thisbe goes out with the plan first to mean by the tomb, but a lion scares her away, and Pyramus thinks the lion ate her. Pyramus, like Romeo, falsely believes his love is dead. Pyramus dies by his sword (Romeo did poison). Thisbe comes back, and she stabs herself with the same sword (Juliet used a dagger, which also belonged to her lover.) In Pyramus and Thisbe, there is an explanation of why mulberries are red: it's because of the blood. Shakespeare didn't use his story to explain an occurrence in nature.