Unity 5.4 (currently in beta), will bring a much awaited feature (since 2013) that is array-textures - in the same vain as OpenGL's ArrayTexture. However, after doing some reading about arrays-textures and texture atlases, I still can't quite understand the technical differences on their usage by CPUs and GPUs.
So, to be more specific, I would like to ask for an explanation on the main differences between how texture atlas and texture arrays are dealt with by CPU and GPU and, most importantly, how such differences can impact on performance and memory handling (e.g. how texture arrays can be more performance than texture atlases, etc).
If technical details on Unity's implementation are lacking due to its unfortunate closed-sourceness, I would be happy enough with an answer regarding OpenGL.s ArrayTexture.