From ATA Scientific:
Scientific terms are often used interchangeably, and scientifically-accepted descriptions are constantly being refined and reinterpreted, which can lead to errors in scientific understanding. While such errors can’t be completely eliminated, they can be reduced by making ourselves aware of them, better understanding the terminology, and using thoughtful and careful scientific methods. This is certainly true when it comes to understanding spectroscopy and spectrometry which, despite being similar, aren’t the same thing. With this in mind, let’s take a deeper look at these terms.
Spectroscopy is the study of the absorption and emission of light and other radiation by matter. It involves the splitting of light (or more precisely electromagnetic radiation) into its constituent wavelengths (a spectrum), which is done in much the same way as a prism splits light into a rainbow of colours. In fact, old style spectroscopy was carried out using a prism and photographic plates. Modern spectroscopy uses diffraction grating to disperse light, which is then projected onto CCDs (charge-coupled devices), similar to those used in digital cameras. The 2D spectra are easily extracted from this digital format and manipulated to produce 1D spectra that contain an impressive amount of useful data.
More here.