I've spent some time researching this subject. I'm preparing for my first hatch. Anyway this site has actual pictures to compare.
http://scienceblogs.com/twominds/2008/04/how_to_sex_a_chick.php
Hope it's helpful.
http://scienceblogs.com/twominds/2008/04/how_to_sex_a_chick.php
Hope it's helpful.