Vertical scaling, also known as 'scaling up', involves adding resources such as CPU and memory to an existing server or virtual machine. It does not require changing the application code or adding more instances, which distinguishes it from horizontal scaling, also known as 'scaling out', that involves adding more servers to handle the load. Elasticity refers to the automated process of scaling resources to match demand, but does not specify which type of scaling is used. Throughput optimization is not a scaling method but rather a concept of maximizing the rate of processing data.