Key difference: ‘Timber’ and ‘lumber’, for most purposes are synonyms. However, they are maybe refereeing to slightly different things, when considering the contexts of American English and British English. For any and all purposes, timber or lumber can be used to refer to any stage of the wood after the tree has been cut down. This may include the felled tree, the wood processed for construction, wood pulp for paper production, etc.

 ‘Timber’ and ‘lumber’, for most purposes are synonyms. However, they are maybe refereeing to slightly different things, when considering the contexts of American English and British English. For any and all purposes, timber or lumber can be used to refer to any stage of the wood after the tree has been cut down. This may include the felled tree, the wood processed for construction, wood pulp for paper production, etc. (See Mahogany Vs. Teak)

Essentially, the term ‘wood’ is used to refer to the trees, specifically, it refers to the substance that trees are made out of. Wood is the hard, fibrous structural tissue that is commonly found in the stems and roots of the trees. However, timber or lumber refers to wood after it has been felled.

Lumber or timber can be either rough or finished. The rough lumber is the raw material, which can be processed and then used for a variety of functions. It will usually require additional cutting and shaping before it can be used. Whereas, finished lumber is the wood that has already been processed and usually cut into various sizes. These pieces of finished lumber can usually be bought and immediately be used in the project without requiring much or any cutting or shaping. (See Rosewood Vs. Teak wood)

In the United Kingdom and other Commonwealth Countries such as Australia and New Zealand, the term ‘timber’ is used to refer to sawn wood products, such as floorboards. However, in the United States and Canada, ‘timber’ usually refers to felled trees, whereas the sawn wood products are referred to as ‘lumber.’ ‘Timber’ may also be used to describe sawn lumber that is not less than 5 inches (127 mm). This is the smallest dimension that timber is available.

The phrase, “Timber!” has also been made famous in modern culture as being the word that is being screamed by bust axe-wielding lumberjacks as a felled tree falls to the ground during logging. It is quite similar to the use of “Fore!” in golf. (Also see: Rubber Wood Vs Hardwood)

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