The low-fat kind are mostly egg whites with extra ingredients added to give the color, consistency, and flavor of whole eggs. As you might imagine, this is a common ingredient in low-fat recipes and dieting guidelines.
Pasteurized eggs are primarily used when serving high risk populations including young children, pregnant women, older adults, and people with compromised immune systems. The pasteurization process eliminates any bacteria or diseases that could be harmful to these people. Pasteurized eggs can also be a good choice in raw-egg preparations like mayonnaise and classic buttercream frosting.
Personally, we tend to be suspicious of egg substitutes in our regular cooking because we never know exactly where the eggs came from or how they've been processed. Many egg products are made with eggs that have been graded B or below either because they're older eggs or are flawed in some way. All in all, we prefer the incredible edible egg while it's still in its original shell.
Do you regularly use egg substitutes? Or are there special times when you'll use them over whole eggs?