हंसः श्वेतो बकः श्वेतो को भेदो बकहंसयोः ।नीरक्षीरविवेके हंसः हंसः बकः बकः ॥Swan is white. So is a Crane. A swan is known for its grace, intelligence and ability to separate milk from water good from the sinister. External appearance may be same. But what differentiates them is that unique talent.