For young children, there's little difference between drawing and writing. Both are wonderful ways for them to explore their creativity, discovering what they are capable of creating with their tool of choice.

How young children draw also changes as they develop. From the early months of random scribbling, where they enjoy discovering cause-and-effect as much as the sensory input from the drawing materials themselves; to the more controlled scribbling when they have better muscles control at around the ages 2 to 3. 

Around age 3.5, children start to be more aware of basic shapes and forms, lines and curves. It's also at this age when you may notice basic shapes starting to form in their drawing. This is also a good time to introduce them to some basic principles of writing, as they are now able to understand that like drawing, writing in all forms is also made of simple lines and shapes.

From the ages of 3 to 5, children also start to develop symbolic thinking, an ability for them to understand that pictures on a page or lines and shapes on paper could be a symbol or a representation of something. This is also a time when they may start to create and draw more purposefully.

At around age 5, they also begin to understand the difference between drawing and writing. They may start to imitate writing characters that they know, or some may even make up their own characters in forms that look familiar. Whether they are correct or not, it's not so important. What's more exciting is to see how they are able to express themselves creatively from an early age using fairly simple tools, and how that expression changes over the years as they develop.