DNKY is much more whimsical and stylized but still clearly conveys the garment design. I love the fun touches of pink for the hair and that the illustrator chose a unique profile walking pose. The figure is exaggerated and long with the focus of the sketch is on the geometric dress pattern.
J.Crew. They both have a loose organic feel with minimal facial rendering and outlined in pen. You can clearly read the texture and fabrics but they both seem casually drawn with a light touch. I love the shadow on the Hellessy illustration, its something I've always admired in Audrey Schilt's Ralph Lauren illustrations.
Cynthia Steffe's illustration is another more stylized and fun one, similar to DKNY. It also reminds me of the Daily Candy sketches by Sujean Rim. (Maybe they commissioned her?) To me it appears the illustration is painted in light washes of watercolor without much line work. The sketch has a very young feel with minimal details but again, understandable garment rendering.
I've broken my picks up by color which today for part 1 here are dusty pinks, muted raspberries and slate blues. Check back tomorrow for another colorway and to see more New York Fashion Week Spring 2015 designer sketches.