I fell yesterday... how do you know if you strained or bruised?

well yesterday, i was riding in a lesson (just me) and well of course the owner's kid came down and was running around with his go cart (it makes a loud noise that scares the horses...) and so he was screaming at his dog like because she was chasing his go cart and he was laughing and so then he'd like run around to the two 5 year old girls and they'd do a high pitched shrill and the dog was barking and the horses were galloping and i was jumping a course so i had to pay attention to my pony, the boy and girls, the galloping horses, the rain (it was raining out), the jump, my position and the course. I'm not the best multitasker so i was going over a jump and i leaned a tiny bit too far forward and was nervous so i wasn't planning on falling off and i fell off of her and landed on the jump with my neck and head hitting the jump and the ground (Yes it hurt!). so i got up right away and not even a moment later did it start to hurt. it felt like a bruise but then it never turned blue. it still hurts really bad today (it hurts to move around with my neck and head...) so how do you no the difference between a bruise and a strain?