Self Confidence is the Assurance you have to go for whatever thing you desire or you want with any struggle or setback while Self esteem would mean whatever feeling that you have, the feeling of worthiness or unworthiness to stay in a particular position or achieve a particular position.

You can have the confidence to apply for a job, go for interview and even get the job but when you get the job and you're beginning to feel do I really deserve to be here or am I worthy to be here, then you're dealing with self esteem here.

To add to that I'll like to ask you few questions that

Are you the type that like to impress everyone and make them feel you're good but inwardly you feel you're not all that good
Are you the type that love to impress everyone and make them feel you're good enough?
Do you attribute most of your success to luck ?
Do you take setbacks personal and think you don't deserve the medal?
Are you reluctant to receive compliments/payment for the service you rendered?

And lastly
Do you desire a revamping self esteem?

If you're any of this, then you should watch it because your self esteem is declining gradually

Now to the question how to build your self esteem

1. The first thing is to spend time on things that add value to you things that help you, improve you.
This brings us to the consciousness of spending at least one hour in a day to to engage in activities that add value, the more you do this, the more you feel better of yourself. You'll become more comfortable to speak at the table without feeling unworthy or undeserving when you're applauded.
That brings us to the question, how many hours do you spend in day to add value to your self?

2. Learn to focus more on your strength while you pay less attention to your flaws.
A lot of us have so much skills, and talent but we'd rather become our self critic and perfectionist than appreciate and showcase our unique endowment. You're beautiful, smart and unique, no flaw should be allowed to bring this value down.
3. We must learn to see ourselves in a unique way that raises our self esteem because self esteem starts from the mind, what you think about yourself and how you see yourself. How you see yourself will help others see you in that light, you can't perceive yourself as someone who is weak, unintelligent etc and expect others to see you the other way... As for your flaws if they're things you have no control over, for instance a body scar, learn to close your eyes to it and if they can be controlled such as your ascent, composition etc then fall back to point 1.

Source-
https://www.youtube.com/watch?v=SBtLqu2ZRQ4