  We show that a site percolation is a stronger model than a bond percolation.
We use the van den Berg -- Kesten (vdBK) inequality to prove that site
percolation on a neighborhood of a vertex of degree $3$ cannot be simulated
even approximately by bond percolation, and develop a decision tree technique
to prove the same for a neighborhood of a vertex of degree $2$. This technique
can be used to obtain inequalities for connectedness probabilities, including a
conjectured inequality of Erik Aas.
