Peek is a verb that means to take a quick or covert look at something. It can also be used as a noun to refer to a quick or covert look. For example:

• She peeked at the surprise party through the window.
• He took a peek at the menu before ordering.

Peak is a noun that refers to the highest point or summit of something, such as a mountain or hill. It can also be used as a verb to mean to reach the highest point or summit. For example:

• The mountain’s peak is covered in snow.
• The company’s profits peaked in 2018.

In summary, peek is a verb that means to take a quick or covert look at something, and a noun that refers to a quick or covert look, while peak is a noun that refers to the highest point or summit of something, and a verb that means to reach the highest point or summit.