both are in the Fungus kingdom and are Eukaryotic. Yeast reproduce by asexual budding and do anaerobic respiration aka fermentation. Molds reproduce both sexually and asexually with hyphae and are primarilly aerobic respirators. Yeast is usually not colored. Molds are usually very colorful. Both have strong aromas. Both can be considered parasites. Both require warmth moisture-humidity and low light for optimal reproduction-growth