This experience shows that a good knowledge of first aid can make a real difference这次的经历证明,掌握急救知识的确能发挥重要的作用
have a good knowledge of 精通；掌握；对…很熟悉
I have a thorough knowledge of the English language.我精通英语.
I have a knowledge of astronomy.我懂一点天文学.
He has a good knowledge of London.他对伦敦很熟悉.
he has a superior knowledge of magic.他有高人一等的魔术知识.
I have only a sketchy knowledge of geography.我对地理只是一知半解.
make a difference有差别,类似地还有make some/no/any/not much/a great deal of difference 有 一些/没有/任何/不太大的/很大的 差别
另外,
tell the difference between 辨别两者的差别
It makes no difference/doesn‘t make any difference to me whether you come here or not.对我来说,你来不来都无所谓.