What types of system scaling exist and how do they differ?

There are two main types of system scaling:

1. Vertical scaling (scale-up) — increasing resources of a single server or node: adding processors, memory, disk space. This allows for performance improvement without changing the architecture, but has physical and economic limitations.

2. Horizontal scaling (scale-out) — adding new servers or nodes to the system, distributing the load among them. This is a more flexible and scalable approach, especially for distributed systems and cloud applications.

The main difference is that vertical scaling enhances the capabilities of a single node, while horizontal scaling increases the number of nodes working in parallel.