Black crush is darker than the black denim. Black denim is, of course, usually the denim material with lighter flecks of gray/denim clearly visible in the fabric...where as the black crush, in my experiences, is the shiny deep black vinyl material that was typically seen on soft tops & tire covers. Very different materials. Hope that helps.
If it doesn't, I'll see if I can find any of your pics and better identify it for you.
ooh looks like Posi beat me to the punch while typing my response.