There are several Landsat data products that are useful for science applications and land use/land change studies:
Landsat Collections Level 1 - Ensures that the data in the Landsat Level-1 archive are consistent in processing and data quality to support time-series analyses and data stacking. Each Level-1 data product includes individual spectral band files, a metadata file, and additional ancillary files.
U.S. Landsat Analysis Ready Data (ARD) - Uses Landsat Collections Level-1 data as input to provide data that is processed to the highest scientific standards and placed in a tile-based structure to support time-series analysis.
Landsat Science Products - Level-2 and Level-3 products that are processed to include atmospherically corrected data, surface reflectance, provisional surface temperature, and biophysical properties of the Earth’s surface.