the rubik's DIY really weren't that different at first, but after they changed the springs and now the center pieces, i think they're pretty much identical now.
but the major diffference is that the original JSK comes assembled and have the weird logo on the white centercap. Rubik's DIY, on the other hand, have the normal logo.
as for JSK clone, it comes pre-assembled and have many different colors. the color scheme is kind of inconventional, it have white, yellow, and blue on adjascent sides
oh and just to tell you, the JSK could have both BOY and BYO color schemes, depending on where you bought it.