As a general rule the 15 metre bleep test is considered easier because the shuttle distance is shorter and the speed progression is smoother. It is normally used by sports clubs, schools and indiduals to help improve fitness, however it is all used by the Police and Prison Service during their career applications.
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The 20 metre bleep test is the harder and more agressive of the two and is favoured by the military (RAF, Army, Marines) and professional sports oganizations such as atheletics, boxing, and football clubs.
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