Braxton Hicks or early contractions?

36w3d.

I am very confused, I’ve been getting cramps almost every night that feel like dull period cramps. Last night didn’t have any cramping. Then today around 7pm, I got one strong period like cramp and it makes my thigh feel weak/tingly, it then went away. Are these Braxton Hicks or early contractions? How can you tell the difference?