I am not a very opinionated person, but when it comes to music, I may have some opinions. My take on this is that there are no untrained musicians. All musicians are trained either by a professional or by themselves. I go around telling people that l’m a self-taught guitarist, but the truth is I’ve listened to others play, watched hours-long YouTube videos, and practiced along with the original song to get where I am now. I am trained in vocal music, and I know that training gives me a more knowledgeable approach. The difference between a trained and untrained, or in this case self-taught, the musician is that a trained musician has always had someone to correct them along their learning process while a self-taught one has to do the learning and correcting all by themselves.
So, to summarise, both types of musicians progress well at their own pace and in my opinion, the trained one is highly likely to grasp musical notes faster.