What is difference between spectroscopy and spectrometry?

Answer 1

Unless you're truly nitpicky, there's no real difference at least in the way the terms are used these days.

Historically, the endings make reference to slightly different processes -- Photography vs photometry is about collecting the light vs measuring it; however spectrometry pretty much had to collect photons from the beginning so the line between the two is blurred.

Outside light-measurements, the -metry ending appears more common in practice (as in "mass-spectrometer") but there, too, usage is not always consistent.

BTW there's a third term, spectrography, which is also used mostly interchangably with the other two these days.

(Note that there are in principle IUPAC norms and any one peer-reviewed journal may just have an editor that is hidebound enough to care about such subtle distinctions -- however using any one of the terms will generally be perfectly understood by any practicioner in any of the various fields and a quick scan of the titles of presentations at the last meeting of the American Physical Society shows a fairly even distributions of the terms even in reference to the same experiment).

Answer 2

Spectroscopy is the study of the interaction between matter and electromagnetic radiation, measuring the intensity of light as a function of its wavelength. Spectrometry is the quantitative measurement of the interaction between matter and electromagnetic radiation, providing information about the chemical composition or structure of a sample based on the analysis of the resulting spectra. In short, spectroscopy focuses on the qualitative analysis of spectra, while spectrometry is more concerned with quantitative measurements.