The thing with calories is they tell you nothing whatsoever about the content of the food - they only provide a total measure of energy. So even if the total calories are the same, there is absolutely no guarantee that they've had the same ratio of nutrients. Fortunately it's pretty easy to figure this out, you just need to look at the nutritional content of the food per 100g (usually displayed on the packaging, if not, there's an abundance of websites with this information) and work out how much has been eaten.

Centesimal composition of the different food you mentioned are quite diverse. Whole milk has lactose (3,2 to 3,5%) (sugar), a constituent that is not present in any of the other mentioned food. Milk has quite different proteins (lacto albumins, caseins, lactogl obolins) all with a very high rate of digestibility (they are easy to digest). Most of the amino-acids are indispensable (quite different from soya proteins) Lipids of milk are also quite distinct (monoglyceride, phospholipids, sterols) (ranging from 0,5 (skimmed) to 3,5 % (whole) in cow to almost 8 % in buffala milk). There are a lot of micronutrients in Milk Calcium, Magnesium, Phosphorous, few Iron) and vitamins (Vit A D E K and from the B complex); all precious for baby nourishment. So in this food “whole milk” energy comes from latose ( 4 kcal/g), Lipids (9 Kcals/g) and from protein (4 Kcal./ g). It is the perfect food for babies and children.

The other kind of food you mention has other nutrients. Proteins from chicken meat are much more concentrated (15 to 21 % depending from the piece of the chicken body) Its digestibility is quite inferior top Milk (70 to 85 % versus 98% in milk) (“white meat”). Lipids may be more concentrated especially under skin. In muscle it rise 2%, most are triglycerides. This meat is power in Iron but with more Potassium and Sodium. Vitamins of the B complex are predominant (liposoluble Vit. are in liver). Caloric value comes from protein and lipids (there are no sugar in meat). Chicken meat in good for those individuals that are in a very active phase of growth (infancy and youngness)

French fries those have significant amounts of protein, only lipids and carbohydrates (it has a lot of energy but is not balanced).

Omelets are also very nutritious, but eggs are better for health when they are eaten cooked. Proteins of eggs are more concentrated than milk and, when cooked, it has a very good equivalence whit milk in terms of digestibility.