What's the difference between GSM vs pounds (paper weights)
Papers are described by their weight, thickness and surface characteristics. The weight is Grams per Square Meter (gsm), which is literally "how many grams would a piece of this paper one meter square weigh?" or "pounds per ream". Of course, very few papers are actually a meter square, but GSM is a very useful way to compare the 'absolute' weight of various sheets of different sizes.
Pounds per ream is rather more troublesome, as it's not at all intuitive. A 65# cover sheet is heavier than an 70# text sheet! And that's barely scratching the surface. Different types of paper have different standard sheet sizes, so cover paper (i.e., thicker card stock) is weighed as 500 sheets of 23x35, whereas bond paper is 500 sheets of 11x17, and 'text' paper is 500 sheets of 17x22.
Aren't you glad you asked?