These words mark the difference between a winning college acceptance essay at Harvard versus Stanford

Each year, the Ivy League and other elite schools receive hundreds of thousands of admissions essays from prospective students.

For most of those students, the secret to writing a winning admissions essay may seem opaque.

Startup AdmitSee has aimed to tackle this problem by giving applicants the ability to read the essays of accepted students, Fast Company reported on Monday.

AdmitSee has a repository of accepted college essays that students can pay to access. They also use the essays to collect data to better understand what each college believes makes a "winning" essay.

Here's the biggest difference between the types of accepted essays at Harvard versus those at Stanford, according to AdmitSee: Harvard accepts students who have more negative words in their essays than Stanford does.

The words "cancer," "difficult," "hard," and "tough" were more common in essays at Harvard, while "happy," "passion," "better," and "improve" were more common at Stanford, according to Fast Company.

AdmitSee also found the content of the essays differed at each respective school.

For Harvard, the admitted students wrote more about overcoming adversity, while at Stanford the essays tended to be about issues that mattered to the students or their family background.

Both Stanford and Harvard utilize the Common Application in their admissions processes. But they also advise students on what they are looking for in essays.

"We want to hear your individual voice in your writing," Stanford explains on its website. "Write essays that reflect who you are; use specific concrete details and write in a natural style. Begin work on these essays early, and feel free to ask your parents, teachers and friends to provide constructive feedback."

Harvard writes that it's looking for "promising students who will contribute to the Harvard community during their college years, and to society throughout their lives."