PMS vs Pregnancy Cramps

What are the differences between cramps you experience right before your start a period and if you might be pregnant?

I’m due for my period sometime between yesterday and tomorrow. No period or spotting yet. I’ve had faint cramps beginning a day or two ago. But I wouldn’t categorize them as cramps - it’s more sore (like if you were to do sit ups) and lower than where I experience normal cramps.

I assume I’m reading too much in to it but was curious what others’ experiences have been. Are there noticeable differences between period cramps and early pregnancy?