What is Plywood?
Veneers (or layers) of wood are taken and stuck together using an adhesive to make a Plywood. These veneers are usually taken from logs of wood.
Quality of plywood depends on the quality of wood that has been taken and the kind of adhesives used and treatments it has gone through. This can then result in commercial (or marine) plywood or waterproof (or BWP) plywood. ISI defines IS303 standard for Commercial plywood and IS710 standard for BWP plywood. Any and each of these ply have usually been treated for resistance to borers and termites.
What is Particle Board?
Factory discards like wood chips, saw dust and wood shavings are mixed with resins and adhesives and pressed together to make Particle Board. Usually, thin sheets of MDF are glued on both sides to make it easy to work and build with. Particle Board may also be called LDF of Low Density Fiber.
Quality of Particle Board usually depends on the strength of the resin used for binding the shavings. Poor quality of resin can result in powder falling off in a very short span of time.
Comparison of Plywood with Particle Board for Interiors
Particle Board is easier for a factory to work with because it is lighter and easier to cut. It is also cheaper making items made with it far cheaper than other products. Particle board is not resistant to water. It can also have issues in holding screws in place since it just has shavings inside.
Plywood is stronger and harder (and heavier). This makes it more difficult to work with. Depending on the grade, plywood is also resistant to water. BWP grade ply can handle flowing water for a very long time. It can also hold screws and nails firmly.
Based on cost, particle board is around 30% to 40% cheaper than plywood on a square feet basis.
Which is better?
For all purpose, plywood is far better than particle board unless the only thing being considered is price. Units made in particle board cannot have a guarantee of working long. In case of polishes like Duco, PU and polyester, plywood is not a good material but then MDF is a better option instead of particle board.