Both terms are used to indicate a woman who is carrying an embryo for someone else. The clinics prefer the word "carrier" to surrogate. I prefer the word "surrogate" to carrier. (I needed a surrogate to get my twins).
A "traditional surrogate" or "traditional carrier" is someone who uses her own eggs and the intended father's or donor (sperm bank's) sperm.
A "gestational surrogate" or "gestational carrier" is someone who uses someone else's eggs or donor eggs and the intended father's or donor (sperm bank's) sperm..
State laws are very variable. You should look them up orconsult a lawyer before choosing a surrogate or carrier.