Don't confuse the meaning of "strut". Many people make this mistake because of the popularity of MacPherson struts which are a very specific device in cars where the support member is also part of the steering system.
Generally speaking a strut is any structural component designed to resist longitudinal compression. How it does so and to what degree it does so is dependent on the designed application.
Shock absorbers, as we know them on motorcycles, are one specific type of strut.
mystic_1
Agreed. In the context of the OP question, having been made on a motorcycle board, I'm guessing he means motorcycle struts which are simply soild rods with no give.
To further the answer to the question, struts on a motorcycle are done for mainly 2 reasons. In the drag race context mentioned, struts will concentrate weight transfer to the rear wheel, whereas a shock would absorb a lot of it, reducing the launch. The 2nd reason as also alluded to, is to mimic a "hardtail" suspension for aesthetics. In reality most hardtail frames are longer and with the seat in the middle, don't provide as harsh a ride as a standard length frame with struts would.
Though I hope to never experience either.