Each has various strengths and requirements to function.
MJ (Minecraft Joules)Edit
Engines output power in terms of MJ/t (Minecraft Joules per tick). One second is equivalent to 20 ticks (assuming no lag). Knowing how much MJ/t an engine generates or a machine uses is key in creating the best system.
You can monitor the temperature of the engine by the color of its core. Blue represents a cold engine, green represents an engine that is warming up, yellow represents an engine that is running at the optimum efficiency, red represents an engine that is in danger of overheating and an engine that is bright red has overheated and will explode if not turned off or cooled down very quickly.
In SMP for beta 2.2.1 of buildcraft, the energy folder should be installed last or the engines won't work properly.
Redstone engines are the most basic engine. When applied with redstone current, it will be powered forever until you turn it off. As of version 3.2 they can no longer be used to power wooden conductive pipes.
This mid-range engine is significantly more powerful than the Redstone Engine but uses burnable fuel, such as wood or coal.
The Chute is an addon block that extends the effective storage of the machine it is attached to. Chutes work best when connected to blocks that have a top slot in their GUI.
Engines - In DepthEdit
Engines can be daisy-chained (As of BuildCraft 3.2, Redstone engines can no longer be chained together). That is, one engine can send its energy to another, which can then send the combined energy to another engine or to the mechanism to be powered. This is useful for charging up the lead engine faster, but incurs a danger of overheating. If the energy is not being removed from the system at about the same rate the system is producing it, the engine at the machine end of the chain may explode. A more efficent way to do this is to use Conductive Pipe. This can be used over longer distances with no chance of exploding for steam engines. Although this is more efficient, it is also more expensive, as energy losses are significant over long distances while using stone conductive pipes, the cheapest conductive pipe that will transport energy.