Generally speaking, coating gets a substrate covered with an applicant while painting (a type of coating) is merely applying a runny or viscous polymer to a surface that may or may not be pre-treated.

Paint is used to protect all sorts of buildings and structures from the effects of water and sun. Wooden buildings such as houses are usually painted because a coat of paint prevents water seeping into the wood and making it rot. The paint also helps to prevent the wood from drying out in the hot sun.