The cells in an onion peel are plant cells, whereas the cells in a human cheek are animal cells.

Both plant and animal cells typically have cell membranes, mitochondria, endoplasmic reticulum, and the nucleus. 

The existence of the chloroplast and cell wall in plant cells is the primary distinction between them and animal cells. 

In-plant cells, the plasma membrane is protected by the cell wall, which is the outermost membrane.