What is the difference between X-ray photoelectron spectroscopy and X-ray absorption spectroscopy?
You could easily google this...

X-ray photoelectron spectroscopy uses low energy monochromatic x-rays to excite electrons from atoms near the surface of a sample. The kinetic energy of the electrons is then measured and then the binding energy of the electrons can be calculated. 

X-ray absorption spectroscopy measure the attenuation of a x-ray beam as a function of x-ray wavelength (or energy). So what you are detecting is the absorption edges of the atoms in the sample.