This type of multifocal contains 2 different powers in the lens. Standard Bifocals typically come in a Flat Top 28(FT28), Flat Top 35(FT35) or Executive. 28 and 35 represent how wide the bifocal is from side to side and Executive represents that the bifocal goes across the entire lens.
This type of multifocal contains 3 different powers. Typically the top power is for distance, the middle power is for intermediate, and the bottom power is for reading. Trifocals also come in 7 x 28, 8 x 35, and Executive.
Instead of having just 2 or 3 lens powers like bifocals or trifocals, progressive lenses provide a seamless progression of many lens powers for all viewing distances. Progressive lenses also have more cosmetic appeal due the invisible zones and no harsh lines like bifocal and trifocals.