Diammonium Phosphate is a form of Yeast Nutrient, so this will be a discussion about the difference between Yeast Nutrient and Yeast Energizer. Yeast Nutrient is a collection of vital building blocks that yeast need to preform healthy fermentation. The process of alcoholic fermentation is an arduous and dangerous task for yeast; they need many nutrients to build a strong colony to complete the task. There are many forms of Yeast nutrient from which to choose from:
Standard Yeast Nutrient - This is a simple nutrient made of food grade urea and diammonium phosphate. It is best used in the last half of wine fermentation. It can also be used as the only nutrient source in musts that are rich in natural nutrients or with yeast strains that have a low nitrogen requirement.
Fermaid K - This is a complex nutrient that provides the full range of nutrients that yeast need to have a healthy and strong fermentation. Fermaid provides DAP, free amino acid, yeast hulls, unsaturated fatty acids, and other helpful products. This nutrient should be added at the start of fermentation, or to aid in restarting stuck fermentation.
Fermaid O - This is a certified organic version of Fermaid K and provides all the same benefits.
Wyeast Yeast Nutrient - This is a specially formulated nutrient for use in low nutrient worts and beer yeast starters.
White Labs Servomyces Capsules -These capsules contain a special mix of autolysed yeast cells that were grown in a micronutrient rich solution. This provides high levels of micronutrients without being toxic to the yeast.
Diammonium Phosphate-This is the simplest form of yeast nutrient and only provides nitrogen and phosphorus. It should only be used in the last stages of fermentation or in nutrient rich musts and worts. Since this is the simplest form of nutrient the yeast will not reach their full flavor potential in most musts.
Yeast Energizer - is a collection of micronutrients and vitamins, it should be used in conjunction with a nutrient source. Energizer should be thought of as a vitamin supplement and used to restart suck fermentation or as a defense against unhealthy fermentation such as off flavors from stress and slow progress.