Pregnancy Tests

Taryn • Married to the most amazing man in the world! :) Trying to conceive our first baby. His 3rd & my 1st - Currently on Clomid 50mg - PCOS affects my fertility - Liberty University- Ultra Conservative Right Wing Republican- Trump Train
I'm not sure if this is the correct group or not but I have a question on pregnancy tests. Is one brand more sensitive than another??
I took a Clear Blue and got an immediate very faint positive on Friday the 6th. On Monday the 10th I took a First Response and got a negative. Has this happened to anyone else? Could it be the difference in brands?