I too had these questions in my mind during my pregnancy days.
Anyway, when it is real contractions, you will feel tightening of abdomen and it will get more intense and more frequent.
I only started my timer to count after an hour of my first contraction because i was unsure if it is real contraction
Honestly, both feels the same. Just that real contraction will get more intense. Whereby braxton hicks is bearable and i only felt it again on the next day.