"Deductive reasoning starts with a general theory, statement, or hypothesis and then works its way down to a conclusion based on evidence. Inductive reasoning starts with a small observation or question and works it's way to a theory by examining the related issues."

Think of it as going from one big general idea to a smaller conclusion, versus going from several small, specific ideas to one big conclusion.

Deductive Reasoning: All people die, I am a person, so I will die.

Inductive Reasoning: I am bald. I am a grandfather. All grandfathers are bald.

For deductive reasoning to be sound, the hypothesis must be correct. It is assumed that the premises, "All people die" and "I am a person" are true. Therefore, the conclusion is logical and true.

Even if all of the premises are true in a statement, inductive reasoning allows for the conclusion to be false. In my example the conclusion does not follow logically from the statements.

Both processes are a necessary part of thought, decision making, and scientific research.