Dear Ruiliang,
I would hope that FAST v7 and Bladed v4.3 could match better than your example plot, but I cannot guess as to what the source of the differences is.
The aerodynamic and structural twists are defined in the following forum topic: Definition of parameters - #5 by Jason.Jonkman. If you only have data on one of the twist distributions, it is often common to assume that both twists are identical.
Best regards,