CB digital vs FR??

Hey everyone.

I was under the impression that clear blue digital was the most advanced test with the highest sensitivity but I notice that most people on this page have been using first response or a test that can show 2 lines. Totally curious as to if theres a reason? I’m assuming its because maybe a vvvfl can be seen on fr but might not be enough to trigger a digital positive? Testing later this week and would appreciate any insight. Thanks girls.