That is a hard question to answer definitively without knowing the nature of the application and the stresses. In general, the composite man-made materials are designed to be stronger in most stresses on a weight or cross sectional thickness basis. I know of a book on this I have at home for designing with material. If you need it, I can try looking up particular materials with a little more info.
Generally real wood is stronger in the cross grain direction. It will not propagate a crack across the fibers of the wood.
Manufactured wood items have no internal graining characteristic. They are the same strength per thickness in any direction (isotropic). Real wood is stronger cross grain than with the grain. When a manufactured wood product begins to fail, it'll usually fail all at once as the crack will rapidly propagate. However real wood will give warning by creaking prior to catestrophic failure and will continue to hold after the initial cracking has started.
As an aside, firemen like wooden beams. The creaking warns them of the impending failure sufficiently to get out while steel and other materials fail without warning and catestrophically.
Glue Lamenant beams have been used for years and are much more structurally sound than same-dimension solid wood beams. I wrote the orginal computer software used by the company that invented GluLam beams to do the cost estimation and pricing.
Mark has it right as well, but don't be confused between "composite" woods like MDF and GluLam beams. GluLam's are solid wood beams that are laminated together. The other big benefit of GluLam's is that they can be bent and are often used in open-beam architecture. Take a look up next time you're in a nice church or office building with wood acsent architecture.
I see those quite a bit in the new construction I have seen. Those who use wood detail anyway. In older construction I have seen where they take boards and bolt them together to make larger beams. The Gluing process must be a large step up in rigidity.
Note: the first two pictures, top to bottom, show the sample woods I bought to match: mahogany, walnut, oak, the bottom is the side of the table. The remaining 3 pictures are of the wood in question...