Raman and FTIR spectroscopy differ in some key fundamental ways. Raman spectroscopy depends on a change in polarizability of a molecule, whereas IR spectroscopy depends on a change in the dipole moment. Raman spectroscopy measures relative frequencies at which a sample scatters radiation, unlike IR spectroscopy which measures absolute frequencies at which a sample absorbs radiation. FTIR spectroscopy is sensitive to hetero-nuclear functional group vibrations and polar bonds, especially OH stretching in water. Raman on the other hand is sensitive to homo-nuclear molecular bonds. For example, it can distinguish between C-C, C=C and C≡C bonds.

I will just add that the methods can be considered complementary. Some of the vibrations of the molecule can be active in infrared and some in Raman.

In addition Raman can be more flexible with regards to sample handling (works with both solids and liquids with mostly no need for sample preparation), sample quantity requirements (less than 0.5mg in some cases) and it can also be deployed in transmission and surface enhanced modes, with the former allowing for better bulk averaging of your samples.

One additional note: As Raman measure relative frequency shifts, its spatial resolution depends on the fundamental frequency. Usually visible or NIR light sources are used, which can easily be focused to spots