What sizes of bricks (building scales) have carried the Lego brand name?
The sizes are:


Regular lego.
Duplo. Intended for younger children than regular Lego. Bigger than regular lego, and compatible with regular lego. Still produced.
Quatro. Intended for younger childern than Duplo. Bigger than Duplo, and compatible with Duplo. No longer produced.
Primo. Intended for babies. Bigger than Quatro, and compatible with Duplo with special interface bricks.
Modulex. Intended for architectural models and commercial signage. Early sets were branded Lego. Not compatible with regular Lego bricks. No longer produced.
Samsonite Jumbo Bricks. Not compatible with regular Lego bricks. No longer produced.
Lego Soft Bricks. Not compatible with regular Lego bricks.