One thing that pops out at me is that in English, the word “girl” has a primary meaning of an underage female, but it can mean any female in certain contexts. For example, you could say that, “My little brother and I played bridge with grandma and Aunt Bessie. The girls won.” You aren’t saying that your grandma is literally under 18 or some other specific age of maturity. You can do the same thing with the word “boy”.
In much formal writing in the US, a “girl” means any female under 18 and any female who is 18 is automatically a woman. For example, “Two 17 year old girls and an 18 year old woman, all sisters, were arrested yesterday for spraypainting ‘Billy Johnson sucks’ on the only bridge out of town.” The fact that they are social peers doesn’t change this in formal writing.
Does this concept apply to any of the Japanese words?