Since ego and pride are often linked, and their definitions are so similar, it can be difficult to figure out exactly how they are different. A simple way to distinguish them is this: ego is rather selfish and often has no basis in fact, while pride tends to be less selfish and is typically based on the facts of a person's achievements and qualities. Some people think of ego as self-respect, and though it can lead to a sense of self-respect, it too often leads to arrogance instead.
When a person has a genuine ability in a particular field, this could be a source of pride. Instead, however, the person may begin to feel that he is the best in this field and that no one else is or ever will be worthy of working with him; he may feel this way regardless of whether or not there's actually any truth to his perceptions. Pride would make this person feel happy about his skills and accomplishments, without having to be the best or only one capable of achievement. It leads to confidence instead of the arrogance.
Ego and pride may also differ in terms of strength. Often, the ego is easily bruised while true pride is harder to shake. For example, ego often comes into play in dating situations. A person's ego may be hurt when a love interest suddenly becomes disinterested or criticizes certain physical attributes. If a person feels true pride in the things that make her unique, however, she may feel disappointed, but her confidence won't take a serious hit; ego is so frail because it is often built on exaggeration.
The two also differ in their effects on relationships. A person's ego may cause him to behave chauvinistically, put down another's attributes, or refuse to date someone whom he feels is beneath him. Often, these behaviors are rooted in hidden insecurities. The ego can mask them but not make them go away. If the person has real attributes to be proud of, however, his insecurities may lessen or at least become less pronounced.
Another difference is that pride may also be focused on others instead of being self-obsessed like ego. For example, a person's ego may cause her to think her children are the most well mannered; after all, how could she have children who are rude or crass? Pride may instead be focused on the things that are special about her children. For example, she might be proud of them for holding doors for other people or volunteering at a soup kitchen. A person can even feel proud of a wide range of other outward things, including her employer, neighborhood, or country.
It's important to note that ego isn't all bad. Ego is simply how a person views himself. If a person's ego has a firm basis in reality and he does not allow it to control his life, it can actually be good for his self-esteem to have both an ego and pride.