These are the two portraits of Julian Tanguy, known as Père (father) Tanguy, the owner of a shop that sold painter's materials and also displayed some artists at the back of his shop. Père Tanguy also sold Japanese printings one of Van Gogh's passion.
You can see at the background some copies of Japanese printings Van Gogh bought at Antwerp. This is a way of depicting Père Tanguy showing a shared interest and creating a new kind of environment and space in the painting.
I have already talked here about the Japanese influence at the 19 century.
You can play finding the differences between the two versions and, please, do you see a pair of glasses at the left coat's pocket of the left painting or is it me?