My OB said it's like having your period with cramps but 100x worse than regular period cramps. They get very intense then go away then come back again every few minutes or so. Start timing them once they start!
My first baby I was unsure, I woke up basically feeling like I had diarhea & that oh my god moment where you feel like your not going to make it to the bathroom in time. I did that every 5 minutes for 20 minutes before I realizied oh hey Im 6 days overdue its baby time.
Contractions are unbearable pain that comes often like you having the time of the month but worse.