The PAH features detected in the infrared range between ~3 and 20um have been extensively used as reliable indicators for distinguishing the dominant energy source of dusty galaxies, such as starburst or active galactic nucleus (AGN). The 3.3um PAH feature is the only PAH feature that will be observable with the James Webb Space Telescope (JWST) at z > 3.5, because the rest of the features at longer wavelengths fall outside the JWST wavelength coverage. However, detailed studies that compare the most frequently used 3.3um and 6.2um PAH features are still limited, because the former was only observable with the AKARI infrared astronomical satellite and the latter was only observable with the Spitzer Space Telescope. In this talk, I will show a direct comparison between the 3.3um and 6.2 PAH feature detected in ~150 local luminous infrared galaxies, which are the best analogs for star-forming galaxies in the early Universe. Then, I will discuss how to adapt these results based on the rest-frame 2-5um range to observe high-z galaxies with JWST.