Partzufim: 2

This combination of the various Sefirot is symbolized by the form of a person (אדם). The Midrash teaches us that the clearest vision seen by the prophets was that of "על הכסא כדמות מראה אדם, On the throne was the form of the appearance of a person." Man incorporates all of the abilities that are found within all the spiritual realms. All of worlds and visions of the chariot are in the spiritual form of Man. It would be impossible to understand the depth of a portion of this form, without an understanding of its entirety.
A person consists of 248 limbs. Imagine if they were all disconnected and piled up. Could someone who has never seen a person figure out exactly how they should be put together, limb by limb? Similarly, without an overarching understanding of the combination of the Sefirot, one will end up with many contradictions as he studies Kabbalistic thought.
This was the main insight of the Ariza"l. He taught the concept of Partzufim, namely that the Sefirot are details in the form of Man which incorporates within it everything of the spiritual conduct of the world. By understanding the greater picture one can then appreciate the depth of each Sefira; what it does as part of the whole. By understanding each Sefira as part of a whole many questions that disturbed earlier Kabbalists are resolved.

Partzufim: 1

The Ariza"l is known to have opened new vistas in Kabbalistic understanding. The most fundamental point which he clarified is that earlier Kabbalists discussed נקודות, individual points, whereas the Ariza"l explained that there were פרצופים, partzufim,  literally faces, i.e. combinations of points, as well.
The fundamental building blocks of Kabbalistic understanding are the ספירות, Sefirot. These constitute ten "colors" of Divine conduct. (Literally, the word Sefirah means clear.) They are the atoms of Creation.
But they do not form the entire picture. The Sefirot only describe individual and very specific ways of God's conduct, חסד, kindness, גבורה, limitation, etc. When this Sefirah is on top, you get this result. When another is in ascendancy there is a different result. They are like points נקודות in which each point has a very limited definition. Each point stands individually on its own and there is no overarching picture.
This viewpoint does not allow you to see the entire picture because God's conduct is actually a combination of different colors all blended together. From all of them emanates one united purpose. The study of the details gives you only a superficial view.