The libpng-devel package contains libraries and header files for developing applications that using the PNG library.
acquired package info from repodata DB: repodata/d96f7206249b192484cd473c7213938a2173442406260d9a32d8f941053a6c53-primary.sqlite.bz2
The libpng-static package contains the statically linkable version of libpng. Linking to static libraries is discouraged for most applications, but it is necessary for some boot packages.