Galaxy M31 don't have Knox but Galaxy A51 have also There Feature not Available in M31 Securityyou will not Get many feature like Samsung Pay, Secure Folder, Samsung Pass, Edge Lighting, Good Lock and Many Other Feature....
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First of all, Difference between 15K and 23K is massive. From Monetary aspect and other features, I think M31 is a good choice. Some major Differences Differences between A51 & M31 I share you. 1) Camera Clarity in both are same though M31 is 64mp. 2) You will find 4K Video recording in both of Rear and Front in M31 but not in A51. 3) In both model there are 8x digital zoom. 4) M31 does not have Knox support, Secure Folder, Samsung Pay, A51 has. 5) A51 Battery Backup is poor but you can use moderately M31 for 2 days. 6) A51 takes maximum 1.5 hours to 100% Charge due to 4000mah. But in M31, it takes 2.5 hours due to 6000mah massive Battery.
As per my opinion, overall M31 is better than A51 in this price segment.
