Occultation is the practice of "covering the ground with an object like a tarp such that light cannot [fuel plant growth]...usually several weeks. This results in the death of the plants and their residues being mostly consumed by worms, fungi and other organisms involved in decomposition. Such that when the covering is removed the amount of work necessary to prepare an area for planting is greatly reduced" (Bare Mt. Farms, 2014). 

Solarization is the practice "of using the sun’s power to control pests such as bacteria, insects, and weeds in the soil. The process involves covering the ground with a transparent polyethylene cover to trap solar energy. The sun heats the soil to temperatures that kill bacteria, fungi, insects, nematodes, mites, weeds, and weed seeds" (Masabni and Franco, 2016). 

A bottom line comparison is this.

Solarization is better suited for quick turn arounds on individual beds between plantings. It kills everything and is not recommended in breaking down cover crops. 

Occultation is ideal for larger plots where the window of opportunity is greater or fields are resting. Additionally, it can be used for turning in cover crops and speeding up decomposition as the temperatures are manageable for bacteria and bugs. 

Resources:

Bare Mountain Farm. (2014, June 28). The Ancient Art of Occultation. Retrieved August 29, 2018, from http://www.baremtnfarm.com/the-ancient-art-of-occultation/

Masabni, J. G., & Franco, J. G. (2016, April). Soil Solarization. Retrieved August 29, 2018, from https://aggie-horticulture.tamu.edu/vegetable/files/2013/09/soil_solarization.pdf

Smith, G., S. B., & Gallandt, E. R. (2017, June 1). Comparing Solarization and Occultation. Retrieved August 30, 2018, from https://gallandt.wordpress.com/2017/06/01/comparing-solarization-occultation/