According to the regulations of ISO, we named the paper as paper which the quantitative is less than 225g/m²; on the contrary, we named it as cardboard. Only a few exceptions. Related departments in our country also approved this standard. This standard about the difference between paper and cardboard is artificially formulated, it is a convention,so it is hard to define it scientifically.
In the old days,on the books of paper-making, printing,and packaging, some thoughts of the division or the difference between paper and cardboard had appeared, differentiate the above quantitative 225g/m² to 200g/m²；plus add the depth regulation as o.1mm, under that named paper; above that named cardboard. But these standards about the difference about paper and cardboard are all outdated,they should not be used any more.
Since we joined WTO, the globalized communications,would have been more frequent than ever before.Thus, play the games with one regulation of ISO about the difference between paper and cardboard will be useful and convenient.