Both are caused by the bacterium Yersina pestis and result in fever and pain. Whereas pneumonic plague affects respiratory organs, bubonic plague is an infection of the lymphatic system. They can now be cured if diagnosed within 24 hours. The severe symptoms produced by pneumonic plague and the fact that it can be spread person-to-person make it especially dangerous. The chances of surviving it in the 14th century would have been almost zero because no medical intervention was available.
Answer by Mike Simpson who is a regular expert in the brain dump section of the magazine.