Evaporated milk is basically regular milk that's been heated to remove about 60% of its water content, leaving behind a creamy, rich liquid. It's a great substitute for heavy cream or half-and-half in many recipes, and it's also a good source of calcium and protein. But here's the thing: it's not sweetened, so it won't add any extra sugar to your recipes.
On the other hand, sweetened condensed milk is evaporated milk that's been sweetened with sugar - and we're talking a lot of sugar. It's thick, creamy, and utterly delicious, but it's also very rich and calorie-dense. So, if you're looking to reduce the sugar content of your recipe, using evaporated milk instead might be a good option.