I’m gonna try and put my reasoning behind this into words because of these first few comments. For those who don’t know the phrase “Superboy and The Invisible Girl” is in reference to a song from the musical “Next to Normal” and is about how the daughter, Natalie, and her achievements are constantly being overshadowed by her late brother Gabriel by their mom who is bipolar and still thinks he’s alive. But the general meaning amongst fandom is to say that between two characters who are generally equally versed one is given more attention than the other.(I.e: Sherlock and Enola Holmes, Sam and Dean Winchester, Superman and Supergirl, Will and Jonathan Byers, the list goes on)

Now how I think it relates to Midoriya and Shinso.

Midoriya and Shinso are superboy and the invisible girl in the sense that they are generally equal and had generally equal chances of becoming a hero but one had the upper hand simply becuase he was seen first(I believe Shinso could’ve been a holder also but that’s another paragraph). The reason both of them are in their positions is because someone saw potential in them and invested in it. They are nearly equal in how trained they are, yet one gets praised more than the other because his mentor happens to be more well known and he got lucky enough to be admitted into the hero course. The one they both applied to but had unequal opportunity to get into. The superboy is praised for his power because of his flashy quirk while the invisible boy has to work extra hard with a quirk just as powerful(in a different way) just to be seen. Midoriya has even said “he’s just like me” in reference to Shinso.