Why some places are called Union Territories?

The Union Territories are those areas which are under the direct control and administration of the Central Government, unlike the states, which share distribution of power with the Centre. 

Therefore, the Union Territories are also known as ‘centrally administered territories’. 

In this way, the existence of these union territories constitutes a conspicuous departure from the federal structure of India. 

Further Reading:

• Union Territories 
• Difference between State and Union Territory