What’s the difference between plain yogurt and sour cream?

This question was asked of me last week, as it would seem that some people don’t know the difference. So let me explain.

Sour Cream: is considered a dairy product as it is basically fermented cream with lactic acid bacteria. This bacteria actually is what makes the cream sour and thickens it. Traditionally, it was much higher in fat than the common sour cream that we buy at the store, which companies use a thickening agent to help make it creamier. High fat sour cream (about 20%M.F.) is still usually made with cream, but the lower fat versions are made more with milk than cream.  It’s not very high in protein or calcium.

Yogurt: There are 3 kinds of yogurt; Balkan-style/Set-style, Swiss/Stirred or Greek Style.

Yogurt is also a dairy product made by using fresh milk that is fermented using yogurt cultures, lactic bacteria. The bacteria is added to heated and pasteurized homogenized milk then incubated. The difference between Balkan and Swiss is the Swiss Style yogurt is stirred prior to the incubation process, unlike Balkan. As for the Greek Style yogurt, the yogurt has been made from milk that has been strained or having the water removed, this makes it creamy.

Now, for Skyr. This is the traditional yogurt of Iceland and quite similar to Greek Style, the only difference is that Skyr is always made with non-fat milk, unlike Greek Style, where it can be made with either non-fat or fat containing milk.
Greek Style and Skyr have been popular for a while now due to their higher nutrient content and their ability to replace sour cream in recipes.
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I like to use either Greek Style or Skyr in Tex-Mex recipes, dips or when making a cream sauce (i.e. Stroganoff). Which do you prefer to use, sour cream or plain yogurt?
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