Scalability <=> High avalability.
Scalability is the ability of a system, network, or process to handle a growing amount of work in a capable manner or its ability to be enlarged to accommodate that growth. cit. Wikipedia.
The differce between this peaks for a lot of time is unused
With AWS Elastic Beanstalk, you can quickly deploy and manage applications in the AWS cloud without worrying about the infrastructure that runs those applications
Aws Beanstalk helps you to manage scalable infrastructure, this type of work adds few problems. This stuff requires a change of workflow, in first because now your application runs in a lot of servers