Difference between Merge Raster Layers and Build Virtual Raster in QGis?

Question

Could you explain the difference between those two functionalities. I have three rasters I want to merge into one. What is the best option ?

Answer 1

Merging your rasters creates a new raster file, effectively duplicating your data. This method uses more hard drive storage space.

The QGIS Training Manual explains the advantages of using a Virtual Raster rather than merging your rasters.

...without needing to actually create a new raster file, which could take up a lot of space. Instead, you can create a Virtual Raster. This is also often called a Catalog, which explains its function. It’s not really a new raster. Rather, it’s a way to organize your existing rasters into one catalog: one file for easy access.