Right now in the House of the Dragon timeline we have so many queens, I know it's hard to keep track of it. But Episode Two of Season Three proved there is a hiearchy, as Alicent drags Helaena to make her heed to the plan and she said it: Alicent might be queen but Helaena is THE queen in their eyes. A Queen Consort, but a queen regardless so here is a little guide.
Queen Regnant. This is the highest-ranking type of queen. She is the monarch herself. She inherited or legally acquired the crown. ex. Rhaenyra, Daenerys.
Titles: Your Grace, Her Grace, Queen [Name] Her Grace, Queen of the Seven Kingdoms. In addition, this depends on who say it but her husband would become either prince consort or king consort, in show, daemon has been refered to as Your Grace in episode 1 and 2 of season three, so it would be king consort.
Queen Consort. The wife of a king. She enjoys royal rank but does not derive authority from inheritance. ex: Cersei, Margaery, Helaena.
Titles: Your Grace, Her Grace Queen [Name].
In the abscence of the King, in real life some of their queens have become regent, as ruling in their place. I doubt this is the case with Helaena but with the abscence of both Aemond and Aegon, she was the highest authority.
Queen Mother. The mother of the current monarch. This is a relationship title rather than a constitutional office. A Queen Mother may or may not be a regent. ex. Cersei was Queen Mother.
Titles: Your Grace, Her Grace the Queen Mother.
Queen Regent. A queen exercising royal authority for someone else. Common situations: King is underage. King is absent. King is incapacitated. A regent can issue orders, command armies, appoint officials, and effectively govern.
Titles: Your Grace, Her Grace the Queen Regent.
Queen Dowager. A widow of a king. "Dowager" essentially means she retains her title after her husband's death. ex. Cersei when Robert died, Alicent after Viserys died.
Titles: Your Grace, Her Grace the Queen Dowager.
From highest practical authority to lowest:
Queen Regnant (actual monarch)
Queen Regent (temporary ruler)
Queen Mother (if influential)
Episode two of season three refered as Alicent as Queen Dowager but also the mother of the king. However, they never used the Title of Queen Mother, so Alicent title would be Queen Dowager.