Freeze-Dried vs. Dehydrate Food

If you're new to the food storage game, you might be wondering why so many emergency prepping companies choose to freeze-dry instead of dehydration for many products. Looking at the process for both preservation methods will help you understand the benefits and drawbacks to both.

The Process
Dehydration-  Dehydrating food is a relatively easy process that can be done from home.  Dehydrators simply circulate hot, dry air across the food removing much of the water (usually between 90-95%) Dehydrating is ideal for grains and legumes.  
Freeze-Dry-   Freeze-drying is a more complicated process. In systems that have only recently become available to households, foods are placed on sheets in chambers where they are frozen to -40 degrees F.  At this point the freeze-dryer creates a vacuum around the food and then warms it. As it's warmed the ice turns to vapor and evaporates.  Freeze-drying removes up to 99% of water. Freeze-drying is ideal for meats, fruits, and vegetables.  Most freeze-drying is done commercially, but recently at-home freeze-dryers have become available.

Shelf Life
Moisture causes food to decompose and grow bacteria. The less moisture in your food storage, the better.
Dehydration - Grains and legumes are ideal to dehydrate because of their low moisture content. However, meats, fruits, and vegetables will retain up to 5% of their naturally high moisture, making it less than ideal for long-term storage (but great for short-term preservation).
Freeze-Dry- Because freeze-drying takes 98-99% of moisture out of meats, fruits, and vegetables, it is the ideal long-term storage option.

Nutrition
Dehydration - The dehydration process can break down several key vitamins and minerals.
Freeze-Dry - The freeze-drying process actually is conducive to retaining all vitamins and minerals except for Vitamin C.

Reconstitution
Dehydration - Rehydrating dehydrated food typically requires boiled water, which can be time-consuming.  However, some foods (jerky, fruit leather, etc.) do not need reconstitution. (Note- Meats should be precooked before dehydrating.)
Freeze-Dry - Rehydrating freeze-dried food only requires water, hot or cold. Like dehydration, freeze-dried meats should be precooked.  However, fruits and vegetables can be freeze-dried fresh. Once water is added, it just takes a few minutes for the food to be reconstituted.

Cost
Typically, because of the easier process, dehydrated food costs less than freeze-dried food.  However, don't compare pound per pound because freeze-dried food is significantly lighter than dehydrated due to the water content.

Texture/Taste
Both foods will retain the original taste. Freeze-dried foods will be softer and airier, simply because there isn't any moisture in the food.