你是不是中国女孩？ s.你是中国女孩吗？ Are you a Chinese girl or not? vs. Are you a Chinese girl? So, it's obvious now. The former can have different meanings depending on the intonation. It can be either a question or a blame. But the latter has only one meaning. it's a questiong and the speaker expects an answer. : )

你指的这两种句子在一般情况下是一样的。但第一种形式某些句子在某些情况下可能带有指责的意思。如：你会不会开车，读的时候由于语气的不同会产生你车开得太烂了的意思。

这牵涉到个人习惯问法哦，所以没有什么很大的区别。但是在第二种局势中的“马”应该改为“吗”。 但是你的第三个句式不能互换哦，因为前者是问会不会开车，问的前提就是你不知道别人会不会开车，才这样问的；后者问开车吗，前提就是你已经知道他会开车。所知只有点三个句式不能互换哦。

这是两种句式，但可以表达同一种意思。可以根据自己的语言习惯和当时的语境来选择该用哪种句式。 不过我建议你用后一种，因为更简洁明了，前一种容易发生歧义。

你吃不吃辣的？ = 你吃辣的吗？ 他说不说英文？ = 他说英文吗？（the latter question is more common.） 你是不是中国人？(another meaning: used when somebody especially a Chinese did harm to China or Chinese people, he would be questioned as that sentence, and you may read between the line as how dare him do that since he is a Chinese.) 你会不会开车？(another meaning: similar as the above sentence: used when a driver behaved badly, and you may read between the line as how did he drive the car to cause much trouble to others since he is already a driver.)