My two cents.
Superstructure design and features can vary due to Navy requirements. The main stealth feature is the relatively low superstructure, flat slab sided feature and low masts. Curved out edges add a bit of stealth but it is not significant.
In addition to a different superstructure design, the Bangladeshi examples are a bit smaller (lower endurance and smaller patrol area) and as a result lower in displacement (1300 tons) compared to about standard 1500 tons of the 056 class. That is why Chinese yard code name for BNS Shadhinota class is "C13B".
C=Corvette
13= 1300 ton displacement
B=Bangladesh
There is a larger but lightly armed OPV variant of the 056 for Nigeria called "P18N" (NNS Centenary class). The displacement is larger because Nigeria's coastal patrol area may be a bit larger (mostly oil rig protection like ours) and they want longer endurance (different naval doctrine from Bangladesh).
P=Patrol vessel
18=1800 tons displacement
N=Nigeria
Most of the following images are from the ship's visit to the primary home of the South African Navy in Simonstown (
Cape Town,
South Africa)