At first they will feel just like period pains, maybe a bit stronger but unlike Braxton hicks (fake labor pains) if you move to try and make them stop, they will continue; as they progress they will be much stronger and you'll know it's actual labor. The way I told my niece to differentiate was like this, if your pain is so strong that you can't move when you're having it, it's time to go to hospital. Good Luck and I hope I don't scare you
If you can't bare the pain, it's real contractions. I know it sounds weird but they feel like bad diarrhea cramps... like really bad.
What made me really realize I was going into labor was back pain, but even then I suddenly started getting the urge to wanna go bathroom (pressure in my uterus) but I wouldn't go. And most importantly which my midwife told me was a really big sign was kind of having a need to lean over and having to catch your breathe every other time. This started happening to me and I was like oh my goodness I think I'm having a contraction. After I got a good read of them being 3 minutes apart I got to the hospital being 7cm dilated . What really helped after they told me I was starting to dilate was going for a walk .