Paper weight is the general thickness of a paper. The greater the paper weight, the heavier, thicker, and sturdier the paper is. Papers with more bulk hold up well when there is heavy ink coverage. For full color photos from your desktop, thicker inkjet photo papers are best. However, some desktop printers may not handle thicker papers well, especially if the printer doesn't have a straight paper path.
Paper brightness affects the images printed on the paper, especially the vibrancy of the colors. The brightness of a piece of paper is typically expressed on a scale of 1 to 100 with 100 being the brightest. The multipurpose bond paper used in copy machines and desktop printers generally has a paper brightness in the 80s. Photo papers are normally in the mid to high 90s.