Windoblinds is a stand-alone program which can utilize graphic card acceleration to be speedy and efficient, and is endorsed by the author of the Operating System it is applied to and intended for.
StyleXP is a 'modified' breaking of the inbuilt 'protection' against unauthorized skinning of the OS, and nothing more, it is not a program, and is naturally not endorsed by the OS manufacturer. It is a dll hack, that allows you use "unautorized" msstyles, therefore it can't offer any funtionality, and is limited in layout cababilities. Also can't be used with an OS other than XP.
Windowblinds has the capability of being applied to more applications and is not dependent on the OS actually BEING 'XP', it works on all 9x, and later OS versions.
For skinners, Windowblinds provides far greater flexibility in skin 'style'/layout, and supports many functional [and useful] additions to the interface that msstyles is inherently incapable of....