Centralisation:
Centralisation refers to the concentration of power and decision-making authority in the hands of a few individuals or a central authority. In a centrally organized system, the decision-making process is primarily conducted by a central governing body or a single individual.

Decentralisation:
Decentralisation, on the other hand, involves the distribution of power and decision-making authority across various levels of an organization or within a larger system. It allows for greater autonomy and decision-making power at lower levels of the hierarchy, giving individual units or departments the ability to make decisions based on their specific needs and circumstances.

Differences between Centralisation and Decentralisation:
1. Power Distribution:
- Centralisation: Power and decision-making authority are concentrated at the top level of the hierarchy.
- Decentralisation: Power and decision-making authority are distributed across various levels and units of the organization.

2. Decision-Making Process:
- Centralisation: Decisions are made by a few individuals or a central governing body.
- Decentralisation: Decisions are made by the individuals or units closest to the specific situation or problem.

3. Autonomy:
- Centralisation: Lower levels have limited autonomy and are bound by the decisions made at the central level.
- Decentralisation: Lower levels have greater autonomy and the ability to make decisions based on their specific needs and circumstances.

4. Flexibility and Adaptability:
- Centralisation: Centralised systems may lack flexibility and struggle to adapt quickly to changing circumstances.
- Decentralisation: Decentralised systems are more flexible and adaptable as decision-making occurs at lower levels, allowing for quicker responses to changes.

5. Communication:
- Centralisation: Communication typically flows from the top down, with little input or feedback from lower levels.
- Decentralisation: Communication is more likely to be two-way, allowing for feedback and input from lower levels in the decision-making process.

6. Accountability:
- Centralisation: Accountability is primarily focused on the central authority or top-level decision-makers.
- Decentralisation: Accountability is distributed across various levels and units, with individuals or departments taking responsibility for their decisions.

Conclusion:
Centralisation and decentralisation represent two contrasting approaches to organizing power and decision-making within an organization or system. While centralisation offers a more streamlined and centralized approach, decentralisation provides greater autonomy, flexibility, and adaptability at lower levels. The choice between centralisation and decentralisation depends on various factors such as the nature of the organization, its goals, and the specific context in which it operates.