**Prime Minister:**
The Prime Minister is the head of the government at the national level in countries that follow the parliamentary system. The Prime Minister is usually the leader of the political party or coalition that has the majority in the parliament.

**Chief Minister:**
The Chief Minister is the head of the government at the state level in countries that follow a federal system. The Chief Minister is usually the leader of the political party or coalition that has the majority in the state legislature.

**Governor:**
The Governor is the head of the state at the state level in countries that follow a federal system. The Governor is appointed by the President and acts as the representative of the President at the state level.

**President:**
The President is the head of the state at the national level in countries that follow a presidential system. The President is usually elected by the people and holds a significant amount of executive power.

**Power Comparison:**

1. **Executive Power:**
- The Prime Minister and Chief Minister have significant executive power as they are responsible for implementing policies and making decisions at the national and state levels, respectively.
- The Governor, on the other hand, has limited executive power and acts more as a ceremonial figurehead representing the President.

2. **Legislative Power:**
- The Prime Minister and Chief Minister have the power to introduce and pass legislation through their respective parliaments and state legislatures.
- The President has limited legislative power and can only veto or sign bills passed by the national legislature.

3. **Appointment and Removal:**
- The Prime Minister and Chief Minister are elected by their respective political parties or coalitions and can be removed from office through a vote of no confidence in the parliament or state legislature.
- The President is elected by the people and serves a fixed term, usually without the possibility of being removed from office unless they commit an impeachable offense.

4. **Representation:**
- The Prime Minister represents the country at the international level and is responsible for maintaining diplomatic relations.
- The Chief Minister represents the state within the country and is responsible for addressing state-specific issues.
- The Governor represents the President at the state level and acts as a link between the state government and the central government.

In conclusion, the Prime Minister and Chief Minister hold more power and authority compared to the Governor and President. However, the extent of their power and influence varies depending on the political system and the specific powers granted to them by the constitution of each country.

Yes, president is powerful and head of the Indian union