Lettuces

A leaf and bud vegetable lettuce grew wild since roman times, but it wasn't until the advent of refrigerated train cars that it could be commercially grown and marketed year-round.
Lettuce is generally grouped into five classes, crisphead (usually but incorrectly called iceburg), butterhead, cos or romaine, and stem.

Greens   a term used for leafy greens that have strong, zingy flavors and they are eaten both cooked and raw.  
Collards, kale, mustard greens, turnip tops, cabbage sprouts, beet tops, dandelion greens, and Swiss chard are cooked in the same manner as Spinach, either chopped, pureed or in some cases raw in salads.

Greens