Yes for some women BH can be quite painful
Normally BH do not have a pattern to them. That is to say that you may get 1 that lasts for 3 mins then the next one may only last for 30 seconds. The time between contractions also is not consistent, it can be anything from a couple of minutes to quite a few hours.
With true contractions each contraction lasts about the same length of time as the one before it. The length of time between contractions are also consistent to a degree. And although this time shortens as you get closer to birth there is still an obvious pattern to it.