What is the difference between elasticity and cloud scalability?

Georg that is not so easy. Some people use both interchangeably. Having onsite ressources aka servers you can scale up and down through e.g. buying or selling those servers. You dont have elasticity available but of course scalability.

Only if you using virtualization and cloud ressources you have both scalability and elasticity. Why? You are able to use in short-term these resources very fast which relates on demand. Therefore, short-term scaling needs elasticity where long-term only use scalability.

I hope that answered your question.