Post any defects you find in the released or beta versions of the ImageMagick software here. Include the ImageMagick version, OS, and any command-line required to reproduce the problem. Got a patch for a bug? Post it here.
I have just run a test and get the same filesize for -resize and thumbnail; adding -strip to thumbnail had no effect either.
version 6.7.6 Q16 run through php on a Vista PC