This is true.
It's not confusing at all.
This.
A calorie is a measurement of energy.
The ammount of energy required to raise 1 kilogram of water 1°C. So if your goal is to raise the temperature of water then yes. A calorie is a calorie, doesn't matter what the source of the calorie is.
But the debate about "a calorie is just a calorie" in bodybuilding has nothing to do with raising the temperature of kilogram of water. Because you feed your body 3 kinds of calories; fat, protein and carbohydrates. Consuming carbohydrates triggers a hormone- insulin- release which makes it harder for your body to burn other calories, mostly fat calories. Carbs compete with fat as a fuel source causing your body to burn carbs for energy and store fat. Then the ensuing insulin resistance that comes with eating too many carbs makes it harder for your body to use carbs efficiently.
Your body requires fat and protein for health, maintain bodily functions including building muscle, repairing injuries, healthy joints and nervous system. On the other hand you can go the rest of your life without eating a single carbphydrate and not suffer any ill effects.
If a calorie were a calorie then drinking 3000 calories of Coca-Cola would get you the same results as eating 3000 calories of orange roughy and we know thats not the case.