Are all cells the same?

No, they're not.  Plant cells are different than animal cells.  Plant cells in a root are different to those in the stem or in the leaf.  Animal cells, including the cells in our bodies are all sorts of different shapes and sizes.

Cells are the units which all organisms are made from.  Different cells do different things.  Some organisms consist of only one cell, like amoeba, or bacteria.  Other, more complex organisms, are made up of lots of different types of cells.  For example, muscle cells are long and fat and work together in bundles to let us move about whereas skin cells are flat and fit together like a jigsaw, covering our bodies.  In contrast, nerve cells are long and thin and can carry messages from one place to another.

Despite all the differences between types of cells, there are also similarities.  For instance, all cells have membranes which allow some substances to pass through, but not others.  All cells contain DNA (deoxyribonucleic acid) for storing information and RNA (ribonucleic acid) for building proteins.  Proteins are used in all cells for forming the structure of the cell itself, and regulating the cells reactions.