True confidence is absense of fear in all situations.
Self-confidence is all about believing we are better than others in some way. One person has a better body, another is a star at some sport, gifted in musical abilities, more educated or has more money than most people. So we cling to our strengths as our identity.
Whatever the particular strength, we then convince ourselves that this is the area of life that matters—this is what we are interested in and, of course, this particular thing is superior to all other traits or interests. Others simply don’t get it!
So the hot girl in the room—while she may only be 19 years old, has little life experience, no money of her own, no accomplishments or even personal freedom—quietly convinces herself that she is superior than the 50 year old woman who has raised 3 kids, accomplished so much, lost so much, been through it all (even being the hot 19 year old once upon a time). How silly, fragile and temporary is the young girl’s sense of self-confidence.
Similarly, the guy with the biggest muscles in town may have a lot of self-confidence from that, but if he finds himself in the company of a group of intellectuals, he may feel stupid and it may erode very quickly. So he keeps to the familiar—tragically limiting his potential.
Total confidence involves no concept of “self”. “Self” is of the ego—based in physical form. It is derived from differences—from the external. It is an illusion that inevitably crumbles and leads to suffering.
True confidence is the absence of fear in all situations. Spiritual or religious people call it faith. I would add that it is the ability to move through the world without letting the external touch you. Confidence is becoming aware that you are eternal consciousness and not physical form. We continue tomorrow and each day after that.