There is not complete certainty on how MBTI and Socionics exactly correspond. The j/p actually means something different, especially for introverts. So while the INFp's NiFe will match MBTI's INFJ, the next two functions, SiTe, match MBTI's INFP, and then, since there is a dispute on the interpretation of Jung on the function attitudes (which was JackFlak's premise), there is a claim that Socionics' NiFe "behaves like" Ne and Fi!
So it would be difficult to say which is more accurate, because they are describing things from totally different angles.
To throw another one in the mix, you have Lenore Thomson's similar "lasagna model":
Here, the shadows are placed inbetween the preferred functions and the tertiary and inferior. This actually will more closely match many people's actual function strengths.
The second model above, which is Beebe's, is not about strength, but rather a stack of the roles the functions play, or the complexes they are apart of. Dominant is hero, aux. is parent, tertiary is child and inferior is soul. The first four will be the positive versions of these, and the bottom four will be negative versions.