Why does it say "Ki Lo Machshevosai Machshevoseichem [v'Lo Darcheichem Derachai]"?
Rashi: Therefore, I tell the Rasha to abandon his way, and adopt My way and My thoughts, to do what is good in My eyes.
Rashi (from Tanchuma Vayeshev 11): My judgment is unlike people's. In your judgment, one who admits is liable; I say "u'Modeh v'Ozev Yerucham" (Mishlei 28:13).
Radak: If a man sins against his colleague, he takes vengeance and does not pardon him. Even if he visibly pardons him, he guards [resentment] in his heart. The visible is called Derech, and the hidden is called thought. I pardon greatly, unlike you, and when I pardon, it is true pardon; nothing remains of the sin.
Malbim: This refutes two claims why Teshuvah cannot be. (a) Hashem does not change. How can He change from anger to satisfaction via a sinner's Teshuvah? About this, it says "you do not know My thoughts." This does not require a change in Me. (b) How can one fix, via regret, what he ruined? If one ruined the king's service, does regret fix it 1 ?! "Your ways are unlike Mine" - I made the Mitzvos in a way that one can fix what he ruined via regret alone, like will be explained.
Malbim: The first claim was based on people's 'investigation' of Hashem's thoughts, therefore it says Machshevosai before Machshevoseichem. The latter claim was based on people's ways, and assuming that Hashem's ways are similar. Therefore, Darcheichem precedes Derachai.