What is an expert? What are some differences between the way experts and nonexperts go about solving problems? How good are experts at solving problems outside of their field?

Explanation
There are some differences between an expert and a non-expert:

An expert has more knowledge about the field compared to the non-expert. Also, since he has devoted his time to learning all that, the pieces of information are organized in his mind and he can access it whenever he wants it. He can also remember it well.
The knowledge of an expert is organized so while solving any problem he will know the first and lasts steps to solve it. For example, an expert mechanic will be more efficient at finding the issues in a car engine as compared to the non-expert.
The expert can spend much of his time analyzing the different parts of the problem. He will try to understand the problem first before solving it. This makes him the best person to do it.
The expert is an expert in his own field. He can perform like any other person outside the knowledge of his field. Also, an expert can be less open to new ways to solve the problem in other fields.

Answer
An expert is a person who has a vast amount of knowledge in any particular field. He has devoted his time and energy to learn about different things in any particular field. He can apply his learning to solve problems in his field.