rightHalf-brother = half blood relative
step-brother = no blood relative
and to clarify even more if either if your parents goes and has a kid with someone that is not your other parent they are your half-whatever. if your parent marries someone else who has kids those kids are your step-whatever.
as a bonus if there is a person who you have interest in if they could warrant a direct invite to your family reunion it is not cool to do them no matter how many times removed that cousin is.
threads like this make me not so proud to be from the great state and are the definition of /facepalm