What are the differences between the APU/Sandy Bridge graphics and all the integrated chips before them?
APU stands for Accelerated Processing Unit a term that AMD usually use, an APU is just really the CPU and GPU integrated into one chip, whereas an integrated GPU is a GPU that's on the motherboard itself.
APU - CPU & GPU Combined
Integrated GPU - CPU and GPU Separate.
Intel has released new CPUs codenamed SandyBridge, these processors have integrated GPUs that stop the need to have an integrated GPU on the Motherboard. Before SandyBridge the GPU was always on the motherboard, therefore the same GPU will be in the system no matter what CPU you have in the board. Now with SandyBridge, the GPU processing is also done from the chip although it's not as powerful but it is useful for systems that don't require a dedicated GPU.
More on Sandy Bridge architecture HERE