The 25K you're referring to is for 9.5-months so is normalized to 9 months to compare against the other 9-month numbers. It's already notated with the [1] footnote in the table.
The 36k is not guaranteed in the offers given to students: the UMaryland CS offer letters states "Students who are TAs or RAs over the summer earn an additional $5,600 up to $11,000", which I can only interpret to mean that 11K is not guaranteed. So what's reported in that table is my interpretation of the minimum stipend if the student does get one, but what you say makes sense, that an RA provides the higher number in that range -- I just don't have a way to represent that.