Answer:
The listener interacts with the speaker in "my last duchess" but doesn't in "Life in a Love".
Step-by-step explanation:
In The Last Duchess, the only speaker is the Duke of Ferrara. The listener, who, offstage, asks about the smile of the last duchess in the portrait, is silent during the entire poem. Still, there's this one sign of interaction between him and the speaker, even though it doesn't happen throughout the poem. In "Life in a Love" however, there's no interactions at all.