From left to right the order is the same in both pictures. Illusion is often based upon our perception and how we use and make meaning from the environment to understand a particular concept. Illusions can be visual or mental. In many cases we prefer a particular vantage point and expand it to the general while we may more accurately assess our environment by taking the general and narrowing it into the particular.
"Subject's unwillingness to deduce the particular from the general was matched only by their willingness to infer the general from the particular" Nisbett and Borgida-Base Rate Fallacy
Think for a moment how people perceive the world. They look at themselves and then project that onto the world, others intentions, and their environment. This is taking our minute understandings of ourselves, which most of us have trouble with anyway, and then making an illusion of the rest of the world. For example, a person who has a particular vantage point may attempt to make understanding of everyone else through this particular lens. This creates a bias about the accurate perception of others.
To be more accurate in your thinking means viewing the world from its macro perspective and then placing yourself within it in relationship to everything else. This requires the ability to perceive the larger picture first and then putting oneself into that picture and understanding how our own personal perception may be different than the information coming from the environment. The bias associated with selective attention diminishes the more we are aware of the larger world.
In the picture we see a cognitive bias. We take the dollar bill and then apply it to the environment. The environment tells us that the largest paycheck is to the right. However, if we were to compare the paychecks against each other, which was the original question, we can better gauge their size relations. We may become aware that the way we view the environment is actually inaccurate because we are using the same paycheck as a vantage point.
One may find the same example in group relationships. If we were to analyze in depth the needs, wants and desires of the group members on an individual level we can find better comparisons between our needs and theirs that help us make better decisions. However, if we assume that the world revolves around us (i.e. a single vantage point) then we only take from the environment those cues that fit within our personal heuristic. Sometimes our first impression and assumption is not the best!