Visual comparison is a key process in everyday learning and reasoning. Recent research has discovered the spatial alignment principle, based on the broader framework of structure-mapping theory in comparison. According to the spatial alignment principle, visual comparison is more efficient when the figures being compared are arranged in "direct placement"--that is, juxtaposed with parallel structural axes. In this placement, (1) the intended relational correspondences are readily apparent, and (2) the influence of potential competing correspondences is minimized. There is evidence for the spatial alignment principle in adults' visual comparison (Matlen et al., 2020). Here, we test whether it holds for children. Six- and eight-year-old children performed a same-different task over visual pairs. The results indicated that direct placement led to faster and more accurate comparison, both for concrete same-different matches (matches of both objects and relations) and for purely relational matches--evidence that the same structural alignment process holds for visual comparison in 6- and 8-year-olds as in adults. These findings have implications for learning and education.