Chainsaws are power saws with a continuous toothed chain driven around a metal bar. They are ideal for cutting large pieces of wood such as trees and branches. Many chainsaws are powered by mixtures of gasoline and oil, but some chainsaws are electric. Electric saws come in battery powered and plug-in varieties. Chainsaws are ideal for tree felling and removal, but they are not precise, so you should avoid using them to cut wood in woodworking projects.
Reciprocating saws have a fixed straight blade that is driven outwards and inwards in a reciprocating motion. Reciprocating saws are commonly used in home and landscaping demolition projects and can be outfitted with a variety of different blades to cut different types of materials such as wood, metal and drywall. Reciprocating saw blades tend to be smaller and thinner than chainsaw blades, but they are not ideal of cutting materials for purposes other than demolition.
Jigsaws are small hand-held saws with small, precise blades that are driven up and down in relation to the body of the saw. Jigsaws are ideal for making precise cuts in wood and cutting out complex shapes and curves.
A circular saw has a circular blade that is spun rapidly by a motor. Circular saws can make clean cuts through wood. They are ideal for cutting wooden building materials such as logs or beams to size in construction projects.
Band saws are power saws that have blades which are continuous loops. The saw drives the blade around a system of wheels and are often used in industrial settings to cut a variety of materials such as wood, metal rods and pipe.