princomp and svd are different?

Hello, Im doing pca using princomp and svd. Here what I can conclude: princomp do pca of centered data and will be equal to svd of centered data; pcacov = svd(cov(data)). What's the difference between princomp and svd, or do they have different functions? (technical details). Are they different with certain types of inputs? Does anyone have matlab code of princomp and svd to see the differences between the two? Thank you