The terms "dry powder" and "dry chemical", is used in regards to fire protection, refering to extinguishing agents.
Civilians, Lay persons and non-fire protection specialists use the terms interchangably. To be exact however, Dry Chemical refers to agents that extinguish Class A, B and C type fires, while Dry Powders refer to agents that extinguish Class-D type fires. Dry Chemicals have the consistancy of a flour like substance. Dry Powders have the consistancy of salt like substances. The difference is obvious to fire service professionals but not so for those who do not come in contact with the substances very often. Even the National Fire Protection Association confuses the issue when they use the word "powder" in their definition of a dry chemical.
NFPA 17 defines a dry chemical as: "a powder composed of very small particles, usually sodium bicarbonate, potassium bicarbonate, or ammonium phosphate-based with added particulate material supplemented by special treatment to provide resistance to packing, resistance to moisture absorption (caking), and the proper flow capabilities."
The chemical formula difference between baking soda and baking powder is that baking soda is sodium bicarbonate (NaHCO3) while baking powder is a mixture of sodium bicarbonate and an acid, such as cream of tartar.
You would not want to use a pressure water extinguisher on any electrical fire due to the possibility of electricity being conducted through the water and injuring someone. A CO2, dry chemical or "clean agent" (e.g., "Halogenated") extinguisher would be a better choice for an electrical fire, knowing that dry chemical powder will make quite a mess.
There are a number of different chemicals. The most common are... Monammonium phosphate, Potassium bicarbonate and Sodium bicarbonate (aka baking powder)
A car extinguisher may be necessary for putting out several different types of fires, so it should be a Class A:B:C extinguisher, normally dry powder. For an irreplaceable classic, one might consider a CO2 or a "clean agent" extinguisher, to avoid the damage potential of dry powder chemical extinguishers.
ABC is the acronym for an extinguisher certified for A, B, and C type fires. A is common fuels like wood, B is for flammable liquids, and C is for charged electrical fires. DCP stands for Dry Chemical Powder, which is inside the extinguisher and is the actual fire suppressant. Basically, DCP is a type of ABC Extinguisher. You can also get extinguishers for Type D (combustible metals), Type K (kitchen), and other specialized extinguishing agents (i.e. Halon). Or you can get a Type A extinguisher, AB, B, BC, ABC, and others even!
wind
One is white
treatment for breathing in fire extinguisher power
You didn't add a second item to compare to. The difference between washing powder for top loading... and what ???
baking powder
Foam, dry powder or CO2 gas- a Class B extinguisher
It depends upon the type of chemical that is burning, but frequently it is safe to use a dry-chemical powder (DCP), or an ABC type of extinguisher. However, boiling grease fires may need a Class K extinguisher and flammable metals (aluminum, magnesium, lithium, etc) may need a Class D extinguisher.