As the name suggests, milk that is classified as "non fat milk" is free from all forms of fat. Aside from the fact that it has no fat, it is also significantly low in calories. This makes it a great choice for individuals who are concerned about weight maintenance or loss, as well as those who are suffering from cardiovascular disease, stroke and certain types of cancer.
In contrast, milk that is classified as "skim" typically is very low in fat, with average fat contents averaging around 1 percent. While a 1 percent increase in fat content may not seem like a lot for the average person, it can be a significant amount for people who are struggling with the conditions described above.
For best results when distinguishing between skim and non fat milk, be sure to read labels both on the containers as well as on shelving on or around the milk. If you have difficulty determining the precise fat content of the milk you are interested in purchasing, talk with an employee or the manager of the dairy section of your grocery store. He or she should be able to help you make the appropriate choice.