Is rendzina soil a podsol or a brown earth soil?

The main difference between rendzina and podsol is B horizon. There is no B horizon in rendzina podsol which is termed as illuvial zone where leaching is most effective. Brown earth soil usually occurs when soil pore space are filled with air. This depends on rainfall , in podsol rainfall is usually higher and so water moves downwards filling the pores with water. Rendzina horizon has more air spaces and so the color is usually brown.