I really have no idea personally, but below are the definitions and example sentences I found for the dictionary entry for bruise in 牛津现代英汉双解词典. I hope this information will be of some use, but I'm afraid it might only add to the confusion until a native speaker chimes in.
n injury caused by a blow to the body or to a fruit, discolouring the skin but not breaking it 挫伤:
He was covered in bruises after falling off his bicycle.
他从自行车上 下来, 满身青一块、 紫一块.
派生： bruise v
1 [Tn] cause a bruise or bruises on (sth/sb) 使（某物[某人]）受挫伤:
He fell and bruised himself/his leg.
Her face was badly bruised in the crash.
2 [I] show the effects of a blow or knock 显出击伤或碰伤:
Don't drop the peaches they bruise easily.