Paper – as it applies to 99% of most peoples’ needs – can generally be described as bond, text, cover, bristol, tag or index. Further, it is more specifically defined by its weight and type, as well as whether it’s coated (e.g., glossy) or uncoated.
And, the way different types of paper is referred to is determined differently for each type of paper. Bottom line, it’s like comparing apples to oranges.
For example, 20 lb bond is referred to as 20lb bond because the weight of 500 sheets of that particular paper – each sheet measuring 17″ x 22″ – weighs 20 pounds. On the other hand, 60lb cover is referred to as 60lb cover because the weight of 500 sheets of that particular paper – each sheet measuring 20″ x 26″ – weighs 60 pounds.
Reams of text and bond paper – when purchased in the US standard of 8.5″ x 11″ – contain 500 sheets. Heavier stock such as cover and Bristol come in reams of 250 sheets.