>>33435451idk man last I checked I could have sworn that May was a glutton of a tomboy who used to loathe Pokemon and tends to have an anger issue. Dawn to contrast is a girly girl who styles her hair and always loved Pokemon and wanted to be a Coordinator from the get go. Compared to May, Dawn is also much friendlier and cuter in manner where as May tends to be more I don't know, boorish maybe?
tl:dr They share similar goals but their personalities are pretty close to being polar opposites.