Like any other modern state, India has two kinds of people—citizens and aliens. Citizens are full members of the Indian State and owe allegiance to it. They enjoy all civil and political rights.  

• Aliens, on the other hand, are the citizens of some other state and hence, do not enjoy all the civil and political rights. They are of two categories—friendly aliens or enemy aliens. 
• Friendly aliens are the subjects of those countries that have cordial relations with India. Enemy aliens, on the other hand, are the subjects of that country that is at war with India.  
• They enjoy lesser rights than the friendly aliens, e.g., they do not enjoy protection against arrest and detention (Article 22). 
• Along with the above rights, the citizens also owe certain duties towards the Indian State, as for example, paying taxes, respecting the national flag and national anthem, defending the country and so on.  
• In India both a citizen by birth as well as a naturalized citizen is eligible for the office of President while in USA, only a citizen by birth and not a naturalized citizen is eligible for the office of President. 

Source: Laxmikanth