In short:
This texture pack combines default Minecraft-Textures and multiplies them by 16.
Every pixel in Vanilla minecraft consists out of 16 hybrid pixels, which can be modified by the Vanilla-Hybrid-Builder
Vanilla Hybrid Builder - Texturepack Tool
The Vanilla Hybrid Builder lets you create your own Vanilla Hybrid pack:
It also contains a download for the old texturpack structure and some more pictures !