Is there a moral difference between masturbation and sex

I know that it is often a lot more fun to have sex than masturbation and it seems to be way more psychologically and emotionally healthy, but I have been wondering if there is a moral difference between masturbation and sex. In my mind, it seems like there is a moral difference, but I have not been able to articulate what that difference is exactly in my mind, or why masturbation is in my mind morally inferior to sex with a spouse or a girlfriend or something. Does anybody else here feel there is a moral difference between masturbation and sexual intercourse, and if so, what is the biggest difference for you, and where does the immorality of masturbation in contrast to sexual intercourse lie in your view. Honestly, I would also be interested in hearing a perspective from anybody who does not believe that masturbation is morally inferior to sexual intercourse if that person is willing to share their view here. Thank you for your perspectives.