In the paper we would like to pay attention to some analogies between Haar meager sets and Haar null sets. Among others, we will show that 0 ∈ int (A− A) for each Borel set A, which is not Haar meager in an abelian Polish group. Moreover, we will give an example of a Borel non-Haar meager set A ⊂ c 0 such that int (A + A) = ∅. Finally, we will define D-measurability as a topological analog of Christensen measurability, and apply our generalization of Piccard's theorem to prove that each D-measurable homomorphism is continuous. Our results refer to the papers [1], [2] and [4].