How do top colleges differentiate between average STEM students?

STEM students applying to top colleges often have somewhere around following set of stats:
2400 Sat
800’s math 2, physics, chemistry
3.8 GPA with non-A’s in art, literature, history
USAMO qualifier
USAPhO qualifier/medalist
Lab Research with regional research awards
Tech internship
STEM related clubs
Numerous regional math/science awards
~100 hours Volunteering

Obviously people like this

Are pationate about stem, but colleges seem to reject and accept these kinds of people. What is the deciding factor here? Is is the essay? What should students show in their essay then?

You are asking this question because you think of top STEM schools in overly narrow terms, and based on what you read here.

Fair enough, there is no average applicant to top STEM schools. Applicants vary considerably. Moreover, schools look for a variety of students. I’m not at all saying that people with the above stats are what schools look for.

Nevertheless, it seems that there are a considerable number of applicants with the above stats on this site. Personally I know people with similar stats who are not on cc. So I think my question is still valid and useful.

No way to predict how a college will differentiate between acceptances and rejections from a pool of worthy high-stat candidates There are also places for strong STEM students who devote time to non-STEM activities (ex. sports, music etc). All you can do is make as strong an application as possible and apply to a wide array of schools.