Team building is a collective term for various types of activities used to enhance social relations and define roles within teams, often involving collaborative tasks. It is distinct from team training, which is designed by a combine of business managers, learning and development/OD (Internal or external) and an HR Business Partner (if the role exists) to improve the efficiency, rather than interpersonal relations. Many team-building exercises aim to expose and address interpersonal problems within the group. Over time, these activities are intended to improve performance in a team-based environment.
Source : https://en.wikipedia.org