What immediately strikes you about the first two iterations is the variation in detail and abstraction. This first one gives us a full composition, where we can look right into this room, perhaps his studio, and make out most elements here. There are glasses, chairs, windows, and so on. Whilst he does not embellish these items with any great amount of detail, we can still certainly identify most of the things in this room. In the followup piece, though, this cannot be said. In that version most items are reduced to an outline, from which we are forced to guess at the different things found here. He does leave some items more obvious, though, which immediately gives them a greater priority in our eyes.
Shortly after his journeys around Zeeland, where landscape painting was his main focus, the artist threw himself head first into the world of Cubism. This period lasted from around 1911 to 1914 and was a key part of his overall movement towards becoming an abstract artist. The two paintings mentioned here give an indication of the changes that were afoot, but he still had quite some way to go before reaching the true abstraction of his neoplasticist period that was to follow. We can also see similar within the progression of his tree paintings, where strong detail and form was eventually taken over by a myriad of line and colour which had long since left any similarity to reality.
Both versions can be found in the Gemeentemuseum in the Hague which itself hosts a fine selection of artworks from Mondrian's career. Those familiar with his abstract work will discover a whole new world here, as they represent his cubist and landscape periods particularly well. Most others works from the artist during this era tend to now belong in private collections and so are very hard to access. Several recent publications have pulled together all of his career works and provide an excellent survey of his career for those unable to travel to see them in person.