Quilting cotton is normally 60-68 threads per inch, higher for batiks, however, I don't know what your website is telling you. Is density threads per inch OR is it yarn count??? Dunno.
I know GSM is grams per meter squared, but I don't know what weight is good/bad.
I would do some research on google as this info is something most quilters don't have info on. We just buy the brands we know.