
Benefits of Box Beams:
- Lightweight
- Easier to install
- Can fully customize the size
- Can hide unattractive elements
How They Are Used
Box beams: A versatile item, these can be used in almost any project to give your space a rustic flair. However, box beams are strictly decorative and should never be relied on for structural support. You should also keep them inside because temperature fluctuations and changes in moisture will make the beam expand and warp.
Weight
Box beams: As we’ve mentioned, box beams are lightweight because they are hollow. This makes them easier to work with and install.
Solid wood beams: These full pieces of wood are very heavy. However, they are also extremely strong and durable, making them ideal for structural support.

Appearance
Box beams: If you study a box beam, you may be able to spot seams connecting the various pieces together. However, this requires a keen eye and getting up close and personal with the wood. Most of the time, especially for ones along your ceiling, you’ll never be able to tell the difference. Typically, box beams have a clean-cut appearance.

source : https://vintagewoodandforgediron.com/about/blog/box-beams-vs-solid-beams/