A dogma is a formally defined teaching of the Catholic Church either by a Pope in a formal statement, ex cathedra, or by a Church wide council of bishops in union with the Pope. A dogma is true and binding for all believers, and it must originate from existing truths of divine revelation.
All dogmas are doctrines, but not all doctrines are dogmas, because dogmas are fully defined in formal statements and doctrines are official teachings of the Catholic Church that have not been formally defined by a Pope or a council of bishops. Co-Redemptrix, Mediatrix and Advocate are Marian doctrines that the Lady of All Nations has asked to promulgate into The Fifth Marian Dogma, but the Catholic Church has not formalized the dogma yet.
The Catholic Church has defined most dogmas to defend doctrines from particular attacks or misunderstandings, and the faithful must believe doctrines just as much as dogmas.