够 or 夠 - Two characters, one meaning?
够 or 夠 shared the same meaning and same pronunciation. We called this situation as 異體字(Variant character). In Taiwan or Hong Kong, we use 夠 more frequently than 够. In Mainland China, they use the opposite one more frequent. All of us can understand both words. 

For more about variant character in Chinese, you may refer to http://en.wikipedia.org/wiki/Variant_Chinese_character