Fingerprint region is used to determine exactly the material in FTIR spectroscopy. If the position of the peaks are unchanged, we can conclude that materials are the same. For changed intensity, the peak intensity in infrared spectra is also affected by the concentration of molecules in the sample shown by Beer's law. Hope that information can help you.
Hi Akankshya Supriya,, As suggested by other researchers variation in peak intensity is due to the concentration of sample in two successive trials. however if there is any shifting in peaks then there is formation of new compound. in addition to finger print reason, concentrate more to assign characteristic absorption bands between 1200-3600 cm-1 (specially if you are analyzing an organic compound).