When looking at domain names made of several keywords, it is often tempting to consider linking them with an hyphen: keyword1-keyword2.com instead of keyword1keyword2.com
From a SEO point of view, there is no difference but it seems that culturally there is. In Germany and France, people tend to favor domains with hyphens, as they find them more legible.
In the rest of the world, the names with no hyphen are preferred.
My advice: if you can, buy both. If you cannot, take into consideration the target market before buying.