IAAF Scoring Tables has them in the same 'ballpark' but with the 800, at 1137 the same at a 4:08.70, while 4:11.01 is 1119, which is the score for 2:01.96. In addition, having a winning time trumps a 5th place finish.
That said, the 1500 is harder at WJr due to the nature of the competition. [the winning men's steeple was 8:06, two seconds faster than the AR.
Just as Ajee has been able to continue to build on her stunning relay 800 (of 2:00) of a couple of years ago, Mary Cain may be able to build on her performances, as well (although there is no guarantee for high school girls).
For both runners, a promising feature is that they are good across a range of distances, although it seems that Cain has a slight advantage in range, but that is more in keeping with someone whose primary event is the 800, since the transition to the sprint side is much more difficult than being within the 1500 range.
Do we actually have to 'choose' between these two; ultimately, it is an artificial 'question'.