If you're asking about the "feature looking at" part, here are a few possibilities of what you might mean:
Performance Improvements: Some clients are rewritten in Python or optimized for HTML5 to provide instant boot times and better frame rates on low-end hardware.
Eaglercraft 1.20 represents a major milestone for the browser-based Minecraft community, as developers work to bridge the gap between the classic 1.8.8 experience and modern "Trails & Tales" features
Because Eaglercraft exists in a legal gray area (it uses Mojang assets but no official code), you won't find it on the official Minecraft launcher. Here is the safe way to access the updated 1.20 version.