Greenwashing is a marketing ploy, akin to whitewashing, where fundamentally toxic and unsustainable businesses exaggerate the value of their environmentally-sustainable and -responsible practices. WalMart, Home Depot and a number of food manufacturers have been accused of greenwashing.
Washing green is, well, keeping your surroundings, clothing and person as clean as possible by using non-toxic materials, often derived from non-petroleum and non-animal sources. Yesterday, the Washington Post ran an article comparing leading green cleaning lines, though I wish more samples from the specific categories were compared.