Is it like this materials are physically based and how light interacts with these materials is via deferred shading?
am i right?
And deferred shading and deferred rendering mean the same?
Deferred shading/rendering has nothing to do with PBR, it’s simply a method of rendering where it separates out the elements of the rendered image (like diffuse, normals, shadows, etc) and composites them together. It’s an alternative to forward rendering where it just renders the image.
Physical Based Rendering is basically using physical models and approximations that are used outside the rendering world to perform the type of rending, roughness for example, it is mainly how the world interacts with color (lightning included :D).
Deferred shading is a strategy or technique to render your objects, it is basically using multiple steps and defer them to produce outcomes that are composed together at the final stage (the second pass). The first step simply gathers information required for the shading process like normals, positions, materials and are rendered for each surface into a G-Buffer (the G stands for Geometry if I recall correctly). In the second pass the pixel or fragment shader will compute the direct and indirect lightning of each pixel using the information gathered in the first pass. One of the advantages of deferred shading vs traditional forward techniques is the amount of dynamic lights a scene can handle. In forward techniques each pixel will be multiplied by each light in the scene while in deferred shading each pixel gets added to each each light resulting in less computations: WidthHeightNumLights (forward) vs (WidthHeight) + NumLights* (deferred). The bad news (not sooo bad actually :D) is that deferred techniques can not apply translucency in the same algorithm which has to be added later or other solutions (UE4 has it solved I guess :D).
Some links about both of them: