First response rapid result vs early result

Jennifer • Boy mom 👦🏻🧑🏻‍🦲with three little 👼🏻👼🏻👼🏻

Do they measure different hcg levels? I took a rapid result 9 dpo and it’s negative but there a shadow. I looked it up and I’ve read mixed reviews that it requires the same level as a digital but idk. Only used early result with all my pregnancies.