The main difference between clinical depression and premenstrual dysphoric disorder (PMDD) is the types of symptoms and how long they last. 

PMDD is a more severe version of PMS where people feel a wider variety of symptoms in a more severe way. This can include sadness, anxiety, mood swings, irritability, and loss of interest in things. Since PMDD is tied to your cycle, people typically find that these symptoms go away once their period starts. 

With clinical depression, the symptoms last for at least two weeks or longer and it’s more often associated with feelings of helplessness and hopelessness, an inability to perform daily tasks or social activities, and a general loss of interest. 

When you’re going through PMDD or clinical depression, it can be a lot harder to see the difference between the two. In both cases, make sure to speak with someone. There are treatments available for both that can help to alleviate symptoms and get you back to feeling like yourself again.