Do contractions tighten your stomach?

This is my second pregnancy and I still don’t know the answer or how to distinguish my BH from early labor contractions. Sometimes what might be BH feels more uncomfortable and crampy in my pelvis and lower back compared to my “normal” painless BH with the belly tightening. The tightening happens also with these more intense BH but idk if it’s actually a contraction or a BH.