contractions or Braxton hicks?

I'm 39+2 -and My belly has been getting tight and uncomfortable.. it's not really painful but tight enough that it's definitely noticeable. Is this just Braxton hicks or the start of early contractions? I've had it happen 3 times since I got to work 2 hours ago, and it happened a few times last night while we were out eating dinner as well. Ftm so I'm not sure what to expect! Haha.