In deciding names for techniques, the currently preferred usage is to identify both the source of the analytical signal and the means for detecting it.
Atomic emission describes all forms of emission from atoms.
These are principally electrons, x-rays and optical photons. So strictly, therefore, AES should include the spectral measurement of all types of atomic emissions. In particular, different types of instruments are used to detect them. Optical emissions are generally detected with optical spectrometers. Thus OES is a part of AES, and all of the techniques of interest could be called AES, but since they all exclusively measure Optical emissions with Optical Spectrometers, the use of OES is much more precise .