Laser copy paper and regular copy paper differ in many ways. Although all good-quality copy and laser papers are designed to run through either machine type, laser paper is designed for optimal aesthetics.
Standard copy paper weight is 20# (lb.), and standard laser paper is 24# to 28#. Both papers are bond papers, and weight is determined by one ream (500 sheets) of 17-inch by 22-inch sheets.
White paper is measured in brightness levels, usually from 80 to 100, with higher numbers denoting brighter whites. Copy paper is around 80 to 85 on the brightness scale, and laser papers are 90 to 100.
Both copy and laser papers have smooth finishes to allow proper adhesion of copy and laser toner. Laser papers typically have smoother finishes than copy paper, in keeping with a higher-quality look.
Laser paper of the standard 24# and 28# variety is thicker than standard 20# copy paper. Weight does not always determine thickness in paper manufacturing, but it is the case with copy and laser papers.
Laser paper has higher opacity than regular copy paper because of material density. Higher opacity minimizes "show-through" of the second side of a printed sheet.
Regular copy paper and laser papers are essentially the same paper type, with laser paper differentiated by higher-quality paper and print attributes. Users should choose which paper to use based on aesthetics and economics.