Idle is an adjective which means inactive

It is also used as a verb in the same sense, meaning spending time without doing anything.

Sentences:

1. The machines lying idle are causing great losses to the company.

2. He is jobless, and thus is usually idle at home.

Idol is a noun used to describe a person who is greatly admired and loved.

Also, it is used to describe an image or a representation of god.

Sentences:

1. The idol of Lord Krishna is made up of gold.

2. Sachin Tendulkar has emerged as an idol for millions of young sportsmen.