One key component of extracurricular activities is whether you commit to them or not. If you were in the web design club one semester, played intramural ultimate Frisbee the next semester, then changed every semester for the entirety of your high school career, this will not be as impressive as sticking with one activity through your entire time in high school. Colleges tend to look for your commitment and consistency to an activity rather than a particular activity. They're more concerned with who you are as a person rather than the minor details of what you actually do in your free time.
Colleges look for exceptional people. That is, people who stand out from the crowd and set the tone rather than follow it. This means that leadership experience is vital. So, if you were the captain of a football team and editor-in-chief of your school newspaper, this is far more impressive than if you were simply a player on the team and a reporter for the newspaper. Again, there is less concern with what you did and more concern with how you did it.
In spite of the above, there are situations where colleges are concerned with what you actually did during your extracurricular activity. If you are applying for a journalism program it looks much better if you were a reporter for the student newspaper than if you were the captain of the football team. This is because in this case the actual skills are more important than the leadership experience.
Ideally, you would be a committed leader in an extracurricular activity that is directly related to the degree you are applying for, but in reality you will likely have to pick and choose from a variety of activities you participated in.
Part-time work and commitments performing volunteer work in the community may not necessarily follow the themes mentioned above. However, they do show your ability to multitask, manage your time and get all your schoolwork done while still working part-time. This is extremely helpful to your application because so much of university study is independent. Nobody is going to manage your time for you at university, and a strong record of work and community service experience will show that you are able to do so yourself.