I know this graphs are not isomorphic. However they have the same number of vertex and edges, and the same degree sequence, is not the most easy case.
If im correct, the graphs are isomorphic if evey posible bijection between vertex preserve adjacencies, then if i find just one bijection in wich some adjacencies are not preserved, that will be enough to show they are not isomorphic?.
Best Answer
In the first graph, none of the vertices with degree $2$ are adjacent. In the second graph, there are two pairs of adjacent vertices with degree $2$.