You have encountered one of the worst examples of ambiguity of meaning in English. To my knowledge, there is no standard defining what each term "really" means. In every case I can think of when someone says "this Friday" or "next Friday" I have had to ask, "Do you mean the Friday at the end of last week, this week or at the end of next week?" In some areas of the US there are regional conventions that are accepted there, but only there. In those areas "next Friday" always means one thing and one thing only. But that standard is not universal. "This Friday" can mean the end of this week or the end of last week. "Next Friday" can mean either of the upcoming two Fridays. All I can say is, if someone uses one of these terms and it's not clear from the context what they mean, ask for clarification. Your request won't be seen as a weakness in your understanding of English, only as a point of clarification. No English speaker, no matter how fluent, can necessarily discern the meaning of either term without sufficient context or clarification.

Haha, I guess it boils down to what your culture and native language dictates 'this' or 'next' week really means. In English, to get rid of such ambiguity, just specify the date and time after you said 'this week' or 'next week'. That's just my opinion, lol. Just wanna add a few links if you want to compare this ambiguity with other languages and culture. =) I found these really helpful! http://www.sinosplice.com/life/archives/2012/04/13/the-perils-of-this-week-and-next-week http://forum.wordreference.com/showthread.php?t=37415 http://painintheenglish.com/case/4650 http://www.englishforums.com/English/NextWednesday/jmnnr/post.htm

In the US, there is a regional difference. In my area of the country, the French part of south Louisiana, “THIS Friday” coreresponds to “THIS week” and “NEXT Friday” corresponds to “NEXT week.” So, we use “this Friday” to indicate the following Friday which comes closest to today, the Friday within a one week period of today. If today is Monday, we say “this Friday” to refer to the day four days hence. “Next Friday” would be the Friday of “next week.” We also sometimes clarify the matter by using the term “this coming Friday” to refer to the Friday closest to today. Those who come from outside my area do not make this distinction. For those people (the ones we used to call “les Americans) “next Friday” would always be the one closest to today.

For example, today is Saturday, week 4. You use "this+day" to talk about all the days that involve in week 4. This rule is same when you match it with morning/afternoon/evening. Ex: This morning, I went to work by helicopter :D So, we use the word next to talk about the days in next week I hope it'll help you :-)

English is not my first language.So anyone please correct me if I'm wrong. I think your sentence should be: What "is" the difference between "this Friday" and "next Friday"? If today is 2013/2/20Wednesday , we say next Friday means 2013/2/22 Friday. Next Friday:the Friday that comes next. This Friday means the Friday in this week, could be past or future day. In this case this Friday and next Friday both means 2/22. What can we say 2013/3/1? Friday next week or Friday week.