Pride, hubris, ego are all sort of suitcase terms and you can probably come up with quite a few different definitions.
Pride, to me, is healthy, but let's not get that confused with hubris, which is damaging. Pride is self-assurance and confidence. You have to hold yourself to some level of standard, and when you meet certain goals it is ok to feel good about it.
When someone else taking joy in their accomplishments and it is externally apparent, some may become upset simply because they might feel inadequate or threatened by such actions, or even jealous. Then again, we have all probably met that one guy who just can't stop boasting about every little thing he does.
However, a healthy person needs to seek self-improvement or at least be humbled once in a while or pride can overwhelm into some sort of sense of being unable to fail or towards an inclination of being inconsiderate to others that are not deemed to be on the same level (I am better than him/her and I know it), that would be the common definition of an inflated ego or hubris.
If you ask the psychoanalysts, the ego is a limiting mechanism to stop the id from going on murderous rampages and humping anything that walks. Sort of a lid or limiter comprised of rational thought to keep our animalistic id at bay. But then, I don't really put much weight on that aspect of Freudian psychoanalysis.
To me, the ego is simply a reflection of how you choose to portray yourself.