What is the difference between "I'm pretty sure" and "I bet"?
"I'm pretty sure" and "I bet" have same meaning?
For example
"I'm sure another opportunity will come."
"I bet another opportunity will come."

What's the difference of nuance between them?

Thank you

Question

What is the difference between "I'm pretty sure" and "I bet"?
"I'm pretty sure" and "I bet" have same meaning?
For example
"I'm sure another opportunity will come."
"I bet another opportunity will come."

What's the difference of nuance between them?

Thank you

Answer

You sound more certain and confident with "I bet"
So you don't doubt 
With I'm pretty sure you aren't as confident as I bet

Answer

They are used the same. You would bet on it because you are pretty sure. They have the same meaning.

Answer

Thank you for every one! It's nice to know it.

Answer

I think it depends on how carefully the speakers spends their money :)

Answer

"pretty sure",  is when you believe you almost know an answer.
"sure" is when you are 100%  confident.
"I bet" is gambling that you know an answer.