This study investigates the diagnostic accuracy of electron temperature and density in low-pressure argon plasmas by comparing line-of-sight averaged spectroscopy with spatially resolved measurements using tomographic analysis. A collisional-radiative model incorporating 65 energy levels was applied to extract local plasma parameters. Using optical fibers arranged around the plasma chamber, emission data were collected and reconstructed through algebraic reconstruction techniques. Results show that tomographic methods capture spatial non-uniformities, while line-averaged methods tend to overestimate values, especially at chamber edges. This highlights the limitations of conventional spectroscopy and the advantages of tomographic diagnostics.