Sample flats are a marketing tool employed by builders. While these can give a hint on how the flat will look, one cannot make a purchase decision based on that.
Location: The best location in the project is chosen for the mock flat so that it overlooks gardens, swimming pools, neighboring projects, highways etc, while the real flat may overlook another block or a boundary wall.
Builders have the right to market their projects using various tools. Home buyers should appreciate that, and factor in everything before making a purchase decision.