The obvious difference between mechanical and wood pencils is the composition. Mechanical pencils consist of a plastic or metal casing and include a spring, lead and an eraser. A wood pencil is usually produced with cedar, which is a durable wood that can withstand certain rigors. Because of its multiple components, a mechanical pencil may be more prone to breaking down. However, a wood pencil can be snapped if enough force is applied. Both pencils have durability issues that can hinder their lifespans.
When a pencil tip breaks or becomes dull, there are different methods for repair depending on whether the tool is mechanical or wood. A mechanical pencil includes a compartment that stores multiple rods of lead. When the tip breaks or dulls out, a simple click or twist of the eraser generally feeds more lead through the head. For a wood pencil, a dull or broken tip requires a pencil sharpener. The wood pencil is placed in the sharpener and twisted until the lead becomes sharp again. This results in another difference between the two varieties; a wood pencil's length shortens the more you use it. A mechanical pencil maintains the same length throughout its use.
In general, mechanical pencils cost more than their wood counterparts; mechanical pencils can be used many times. Wood pencils eventually dull out and reach the end of their use. A mechanical pencil can be refilled multiple times with lead.
Mechanical pencils typically provide a greater consistency than wood pencils. The lead in a mechanical pencil stays even and can be quickly replaced. With a wood pencil, pressing on one side of the pencil will dull the lead out, resulting in a slight change in the consistency of the markings. A pencil sharpener is a necessity for wood pencils to maintain consistency.
The lead in a mechanical pencil is generally thinner than a wood pencil. For a mechanical pencil, lead diameters typically come in 0.3 mm, 0.5 mm, 0.7 mm and 0.9 mm. Generally, the largest mechanical pencil lead is 2 mm in diameter, the same measurement as most wood pencils.