Contractions or Braxton Hicks?

I’m 37 + 4, been having on and off pains in my lower abdomen and groin area, lasts about 60 seconds, stomach hardens up during this time then softens again - feels like period cramps/sharp pains. I can sleep through them, but when awake comes and goes every 30 mins or so. How do I tell the difference between this and braxton hicks? ☺️