"The really big difference is that what you make with a molecular machine can be completely precise, down to the tiniest degree of detail that can exist in the world"

This quote by K. Eric Drexler is referring to the capacity of molecular devices. Molecular machines are devices that are comprised of molecules and can performing complex tasks. The quote is emphasizing the precision that molecular devices can achieve. Molecular makers can create products with a level of detail and accuracy that is not possible with standard devices. This level of precision is because of the fact that molecular machines can control molecules, which are the smallest systems of matter. This indicates that molecular devices can develop items with a level of information that is not possible with standard makers. This level of precision is what sets molecular makers apart from conventional machines and makes them so powerful.