This distinction concerns the content of judgments. Milk contains calcium. All children ought to drink milk. A distinction that concerns what makes a judgment true , with concern to how the predicate is connected to the subject.
Judgments are true in virtue of the concepts alone.
The negation of an analytic judgment is a contradiction. A judgment is analytic if it is not synthetic. Synthetic judgments provide us with non-definitional information about the subject. These statements tell us something about dogs, swans, or triangles which might some day be very important to know. It is an epistemological distinction.