Q: What is the difference between ego and self-esteem? "Ego" seems to generate all sorts of problems, whereas everyone needs good "self-esteem."
A: "Ego" has several meanings, depending on context. If you're discussing "ego" as a part of someone's psychic anatomy that just got bruised, then it's interchangeable with "self-esteem." "Self" is another definition of ego, and Freud had his own definition.
I suspect the guidance you're looking for isn't semantic, though. It's emotional: When does good self-esteem go bad?
Ego and self-esteem are the bond between who you are and who you perceive yourself to be. When your ego (or self-esteem) is healthy, you have a realistic idea of your strengths and weaknesses. When your ego (or self-esteem) is unhealthy, there's a breakdown in one of two directions - you have significantly more, or less, going for you than you think.
To assess your own health, think of ego as the security guard while self-esteem is the institution it protects. If the institution - the self - stands soundly on its own, built by hard work, a sense of purpose and a sense of accomplishment, then it doesn't need to hide behind a huge security/ego system to protect it. The result is a person who can shrug off failure, say, or rejection, or who can perform a so-called menial chore without fear of being lessened by it. It's not needing a constant supply of approbation. It's what people mean when they say, "S/he has no ego."
When the institution of self is shaky - when a person is praise-dependent, or feels unworthy - that's when it's paramount to appear strong. Enter the ego staff, either to gin up bravado, or to churn out pre-emptive apologies; to create and shore up your appearance of invulnerability, or to tear you down before anyone else gets the chance to; to decline to admit being wrong, or to scour for new ways you can blame yourself; to attempt to control others, or to latch on to someone else; to chase away people who might get to know you too well.
Gauging your health may be as simple as checking your own maintenance program, for lack of a better term. When your view of yourself is clear, your instinct for self-preservation motivates you to take care of yourself, and/or the people around you. When your view of yourself is distorted or obstructed, that instinct is deployed for the sole purpose of maintaining everyone's image of you - and, alas, to shooing scary self-knowledge away.
How - and when - to lead a friend out of La-La Land
Q: My friend's boyfriend broke up with her. It seems pretty clear from his actions that he does not want to get back together, but she is clinging to this possibility. Should I try to convince her it's not likely? So far I've been trying to distract and not encourage her when she talks about him.
A: It's not really your place to "convince" her of anything; after all, you don't know the ex's intent, you just know what you've seen and heard.
However, you can ask her, conversationally, what she has seen and heard: "Really? What has he done that has you thinking you'll get back together?" Elicit facts, not hopes - there's a better chance her hopes will resemble those facts. Otherwise, you just do some waiting and hoping yourself.