I am currently studying QFT and have a problem concerning the 2-point correlation function in $\phi^4$-theory. When I draw all the Feynman diagrams contributing to $\left<\Omega|\phi(x)\phi(y)|\Omega\right>$ (so without the vacuum bubbles) up to $O(\lambda^3)$, I get the following:
However, I am not sure about the ones in the curly brackets. Are those the same diagrams? If so, how does the symmetry factor account for them?
I tried to find an answer to this, but nobody draws the third order diagrams.