# Why do planned comparisons and post-hoc tests differ?

I conducted a three-way independent ANOVA. I manipulated the sound of my stimulus to be 1: congruent (KON), 2: incongruent (INK) and 3: no sound at all (control condition). One of my planned comparisons, the incongruent (INK) vs. the congruent (KON) sound is in essence a post-hoc test, isn't it? As, in both cases, I am comparing two levels of my manipulation. Yet, the results I get differ.

PLANNED COMPARISONS

                                         Df  Sum Sq   Mean Sq  F value  Pr(>F)
Manipulation                              2   12.34   6.170    2.473    0.0902 .
Manipulation: control vs. Experimental  1    9.21   9.206    3.690    0.0580 .
Manipulation: INK vs. KON               1    3.13   3.133    1.256    0.2655
Residuals                                88  219.54   2.495


POST-HOC TESTS

Tukey multiple comparisons of means 95% family-wise confidence level

\$Manipulation
diff       lwr        upr     p adj
KON-INK  0.4506173 -0.508031 1.40926557 0.5040074
NS-INK  -0.4960317 -1.444847 0.45278399 0.4293551
NS-KON  -0.9466490 -1.962296 0.06899754 0.0730128


Pairwise comparisons using t tests with pooled SD

    INK   KON
KON 0.797 -
NS  0.648 0.087

P value adjustment method: bonferroni


So what really confuses me is that the difference between KON - INK in case of the planned comparision has a p-value of 0.2655, in case of the Tuckey HSD it has 0.5040074 and in case of the pairwise comparision with bonferroni correction, it has 0.797.

Where are these differences coming from? Or where is the flaw in my logic?