The 4G Evolved Packet Core is built from monolithic network elements — MME, SGW, PGW — each deployed as a dedicated appliance connected through rigid point-to-point interfaces using Diameter and GTP-C signaling. Scaling requires adding entire nodes, and a single failure can cascade across tightly coupled components. The 5G Core replaces this model with a Service-Based Architecture where every Network Function exposes its capabilities as HTTP/2 microservices on a common bus. Any NF can discover and consume services from any other NF through the NRF, enabling independent scaling, rolling upgrades, and true cloud-native deployment on commercial off-the-shelf hardware.