React + GQL: Work is done on the client and chooses how to render, the server sends 1st page, API connections deliver ongoing data. Smaller data transfers, only sends what’s needed. Faster interaction due to on-device updates. CPU & Memory use largely down to clients. Cost effective scales smoothly.

PHP: Server-side rendering (Legacy method) – Server does work and sends the pre-rendered page to the customer. Large data transfers, slow interaction, high server use. Some javascript is used for presentation.