Yes, it does mean the same. There was actually a lengthy discussion about this word yesterday, following someone's query about the expression 'Kiss my ass'. I'll give you the British perspective. The word 'arse' has a long history. It's a fine old Anglo-Saxon word, related to the modern-day German word 'Arsch'. It's been used in the British Isles for many centuries, and in fact first appeared in the Oxford English Dictionary as far back as 1480. The spelling is always the same, and it's pronounced either with a long 'ah' sound (for example in most accents in England) or with an 'ar' sound (rhotic) in other parts of the British Isles, such as Ireland. The word 'ass' in standard British English means a donkey. So, if you come across a conversation in a book where one person says to another 'Don't be an ass', it means don't be an idiot - referring to the animal rather than the body part.