[Q] difference in PDA topic

Hello all.

I would like to kindly ask what is difference:

Romania (Vodafone) (CNX) SM-G900F GALAXY S5 4.4.2 G900FXXU1ANH4
Romania (Vodafone) (CNX) SM-G900F GALAXY S5 5 G900FXXU1BNL9

ANH - BNL <- what are toose?