Some people consider there to be four types of "yarnovers"
between a knit and a knit stitch - yarn starts in back, goes between the needles, and back over the needle.
BEtween a knit and a purl stitch yarn starts in back, goes between the needles to the front, over the needle to the back, between the needles to end up in front for the purl.
between a purl and a knit stitch - yarn starts in front and goes OVER the needle to the back
between a purl and a purl stitch. yarn starts in front, goes OVER the needle to the back, and back between the needles to the front.
The actual yarnover is the loop over the top of the needle; which is the same in all four cases.
MMario - *REAL* men knit LACE