We present the detail comparative systematic study using a sample of 200 Narrow-line Seyfert 1 (NLSy1) galaxies in comparison to a redshift and luminosity matched sample of 132 Broad-line Seyfert 1 (BLSy1) galaxies based on their observations using ROSAT and/or XMM-Newton telescopes in soft X-ray band (0.1-2 keV). A homogeneous analysis is carried out to estimate their soft X-ray photon indices (Γ_sX )
and its correlations with other parameters of nuclear activities such as Eddington ratio (R_Edd), bolometric luminosity (L_bol), black hole mass (M_BH) and the width of the broad component of Hβ line (FWHM(Hβ)). In our analysis, we found clear evidence
of a difference in the Γ_sX and R_Edd distributions among NLSy1 and BLSy1 galaxies,
with steeper Γ_sX and higher R_Edd for the former. Such difference exists in the spectral
indices distribution in hard X-ray (Γ_hX ), based on the analysis of 56 NLSy1 and 51
BLSy1 galaxies in the 2-10 keV energy band which is less prone to be significantly due to the soft X-ray excess. The difference in R Edd distributions does exist even after
applying the average correction for the difference in the inclination angle of NLSy1
and BLSy1 galaxies. We also estimated R_Edd, based on SED fitting of 39 NLSy1 and 40
BLSy1 galaxies over the 0.3-10 keV energy band and found that results are still consistence with R Edd estimates based on the optical bolometric luminosity. Our analysis suggests that the higher R Edd in NLSy1 is responsible for its steeper Γ_X compared
to the BLSy1, based on the expectation of disc-corona model similar to the luminous
AGNs. Furthermore, the positive Γ_X − R Edd correlations found for both the samples
of NLSy1 and BLSy1 galaxies in both the soft and hard X-ray bands suggest a similarity in their X-ray emission mechanism.