The graphic design is basically the same... the difference is tactile and mainly noticable in the quality of the production. For example, Black Sparrow used relatively high-grade acid-free papers for the text block while Ecco uses a cheaper, thinner paper. Ecco uses this slick, plastic-like stock for the covers while BSP used paper similar to a good quality charcoal art paper.
When you hold a BSP book you get the sense that a lot of care went into it's production while Ecco books just feel mass-produced.