Optical cable directly buried and optical cable laying in the pipeline are two common ways of optical cable laying, they have some differences in installation methods, protection measures, maintenance costs and application occasions:

Installation method:
Optical cable direct burial: The optical cable is directly buried in the soil, usually according to the specific depth and width of the excavation of the trench, and then the optical cable is laid at the bottom of the trench, and covered with soil.
Pipeline laying: It is first to lay the pipeline (can be plastic pipe, metal pipe or concrete pipe, etc.), and then the optical cable is inserted into the pipeline. Pipes can be embedded in roads, buildings, or other structures, or they can be laid by digging separate trenches.
Protection measures:
Optical cable direct burial: Because the optical cable is directly exposed to the soil, the outer protective layer of the optical cable is higher, and a thicker sheath is usually required to resist mechanical pressure, chemical erosion and biological damage in the soil.
Pipeline laying: The optical cable is placed inside the pipeline, so the requirements for the outer protective layer of the optical cable are relatively low. The pipe itself provides physical protection, reducing the impact of external factors on the cable.
Maintenance cost:
Optical cable directly buried: Once the optical cable fails, it is more difficult and costly to maintain, because it needs to re-excavate the trench to find the fault point.
Pipeline laying: The cable in the pipeline is easier to replace or repair, just open the connector of the pipeline, no large-scale excavation is required, and the maintenance cost is relatively low.
Application:
Optical cable direct burial: suitable for long-distance, open terrain and not too many obstacles laying environment, such as rural areas or urban peripheries.
Pipeline laying: Suitable for dense urban areas, under busy roads, built-up areas or other places where the cable needs to be protected from mechanical damage.

In summary, optical cable direct burial and pipeline laying have advantages and disadvantages, and the choice of laying depends on the specific engineering needs, environmental conditions and economic budget.