We write 頭 and 顔 for the meanings of head and face, respectively. The common component for the two is the right one 頁, which originally comes from a human head. Today I'll introduce these two characters.

(1) 頭 (atama, head)

This Kanji character means a head or a certain top for many things. We sometimes say "Toubu (頭部)" for the meaning of a head region. Or, "Sentou (先頭)" represents a lead in a procession or competition.

How was this character was born? Take a look at the attached picture. The left part is from a serving dish whose foot is thin and long, but the head is relatively big.

The second part on the right is from a human head and face.

Thus, the human head lies, like the thin and long dish, on the top of a human body. That's how it was created.

In addition, the component "頁" is named Ogai in the language, partly because the Kanji 貝 (Kai, shell) is used on it. A few people might write Ogai like 大貝 (big and shell), or others will spell it in Hiragana syllables, おおがい. When this particular part is used, the outcome means a condition or name related to a human head.  

For your information, the left part itself reads Mame (豆), a symbol for beans.

(2) 顔 (kao, face)

The next character associates with a human face in many cases.

How it was generated is a person who preens oneself. On the left part, it comes from a person who smiles, wearing a fancy clothes.  Dressed well, they get their makeups or put drawings on their faces or foreheads when they come of age.

Those cosmetics come up with the character 顔 (face). Here as well, the Ogai component is used because it relates to a human head.

Did you tell the difference between the two characters? One is the bigheaded, and the other is the fashionista.