Consolidation:
Consolidation refers to the process by which soil particles are rearranged and compressed under a load, resulting in a decrease in volume. It occurs over time as excess water is squeezed out of the soil, and the particles settle closer together. This process is mainly due to the compression of air-filled voids and the expulsion of water from the soil.

Compaction:
Compaction, on the other hand, involves the application of external forces to soil to increase its density and improve its engineering properties. It aims to reduce the void spaces between soil particles, resulting in increased shear strength, decreased compressibility, and improved bearing capacity.

Differences between Consolidation and Compaction:

1. Process:
- Consolidation is a natural process that occurs over time due to the self-weight of the soil and applied loads.
- Compaction is an artificial process that requires external forces, such as mechanical compactors or rollers, to increase soil density.

2. Time:
- Consolidation is a time-dependent process that can take months or even years to complete.
- Compaction is a relatively quick process that can be achieved in a matter of hours or days.

3. Volume Change:
- Consolidation results in a decrease in soil volume as water is expelled from the soil.
- Compaction typically results in a slight increase in soil volume due to the rearrangement and reorientation of soil particles.

4. Water Content:
- Consolidation is primarily influenced by the excess water content in the soil, which is gradually expelled during the process.
- Compaction is not directly affected by the water content, although optimal moisture content may be required for achieving the desired compaction level.

5. Effects on Engineering Properties:
- Consolidation mainly affects the settlement behavior of the soil, which can lead to long-term settlement and potential structural damage.
- Compaction improves the strength, stability, and load-bearing capacity of the soil, making it suitable for construction purposes.

In summary, consolidation is a natural process that occurs over time and involves the expulsion of water from the soil, while compaction is an artificial process that increases soil density through external forces.