In a case-control study examining the association between oral contraceptive use and venous thromboembolism, the odds ratio is calculated as 3.5 (95% CI: 2.1–5.8). In contrast, a prospective cohort study on the same exposure-outcome pair reports a relative risk of 2.8 (95% CI: 1.9–4.2). Which feature best distinguishes the odds ratio from the relative risk in this scenario?