I will comment briefly, and if anyone wants to develop my comment further, please do so.
Dogma is truth necessary for salvation (e.g.: Jesus is God).
Doctrine is not absolutely necessary for salvation, but is logically derived from Dogma (e.g.: Purgatory).
There is a third entry in the “Hierarchy of Truths” (that is, the relationship between Dogma, Doctrine, and Discipline):
Discipline is a practice which the Church has implemented, after She has discerned it is best for the members of the Faithful (e.g.: Priestly celibacy; Fasting).