I'm pretty sure "Romantic" Two-Girl Friendship is the one without sex, at least that's how it's conceived in 19th century works.
I thought Schoolgirl Lesbians was just "lesbians in high school", often with a fanservice element. The couple who are the page image definitely get physical. Plus, there's this line in School Girl Lesbians:
It's just poorly worded, actually. Read the line from Schoolgirl Lesbians again, with my emphasis added:
Both tropes indicate that Schoolgirl Lesbians is the more sexual one.
-_- double-negatives are bad -_-
So it seems like Schoolgirl Lesbians is the more physical one? I agree, the wording is a bit awkward.
"Thus, it is not uncommon to find teenage girl-girl relationships in Japanese media—unless they explicitly describe themselves as lesbians, or engage in physical intimacy (at least kissing), it's not this trope but a Romantic Two-Girl Friendship instead."
Here's my attempt at rewording it: "If this "Class S" relationship starts going physical, however, it stops being a "Romantic" Two-Girl Friendship and starts becoming this trope."
(The blurb before this has a pothole to RTGF and an explanation of "Class S" relationship)
We can never truly eradicate the coronavirus, but we can suppress its threat like influenzaClass S can go so far as kissing but that's it. The major point of Class S is they are not actually lesbians and never get together and after the story they go off and have relationships with guys.
Schoolgirl Lesbians and "Romantic" Two-Girl Friendship refer to each other as "when the girl-girl relationship gets physical". Yeah.
We can never truly eradicate the coronavirus, but we can suppress its threat like influenza