Sometimes I come across the question tag REU MAI หรือไม่, which seems quite similar to หรือเปล่า.

Some examples:

ไม่แน่ใจว่าหลังการเลือกตั้งบ้านเมืองจะวุ่นวายหรือไม่ ไม่แน่ใจว่าจะเกิดอะไรขึ้น

"It is very uncertain whether our country will become chaotic after the election; we are uncertain as to what might occur."

http://www.thai-language.com/id/149374

From a written English test for Thais; my translation in brackets:

homely เป็นคำวิเศษณ์ใช่หรือไม่ [is the word 'homely' an adverb?]

เราใช้คำ informations และ luggages (รูปพหูพจน์) ได้หรือไม่ [Are the plural forms 'informations' and luggages' correct]?

สำนวน of course not ใช้ในการเขียนหรือไม่ [is the expression 'of course not' used in writing? (as opposed to just colloquially in speech)].

เมื่อกล่าวถึงบางสิ่งว่า ostentatious เราแสดงน้ำเสียงเห็นชอบสิ่งนั้นหรือไม่ [When we talk about something being ostentatious, does it imply approval or not?]

Can หรือไม่ and หรือเปล่า be used interchangeably, or is there a difference? Perhaps in formality, written /colloquial usage etc.

eg

I've heard คุณเป็นคนไทยรึป่าว. Can you also say คุณเป็นคนไทยรึไม่?

Or ชอบรึป่าว ชอบหรือไม่

Is there a difference between the two forms? I'm trying to get a feeling for when หรือไม่ is used.

Thanks in advance.

Edited April 19, 200917 yr by merck

After looking at my two Thai grammar books I've found the following:

David Smyth simply lists หรือไม่ as a variant of หรือเปล่า.

James Higbie suggests it is more formal and used mostly to replace หรือเปล่า in writing.

Higbie also has หรือไม่ listed as a conjunction meaning 'or if not' i.e. คุณเอาให้ผมหรือไม่ก็ฝากเพื่อนไว้ก็ได้.

Looking at your two examples this certainly seems to be the case. Personally, I'm pretty sure I've heard it in speech quite a bit, but certainly not as much as หรือเปล่า

Edited April 19, 200917 yr by withnail

I essentially agree with Higbie although as withnail points out it IS used in speech too, just not as much as หรือเปล่า .

Ditto what Meadish said, and another thought - while ไม่ has certainly one function, grammatically, and one meaning, เปล่า also has another lexical meaning (say, "empty", or "de/void of") while their grammatical functions can be similar or basically the same, เปล่า is not just a negative particle (please forgive my broker linguistic English).

Thanks withnail, meadish_sweetball and Barabbas.