Hi Seattle2012 - the short (and not helpful! ) answer is: It depends.

Every school expects/requests different things. For example, Columbia doesn't want any college internshps listed in the online dataset; they tell you to inform them of those in an optional essay. This is the exception though, for most schools you should, in fact, include summer internships in the online data. In most cases you would skip any jobs that are not directly related to your career though. So, if you were a bartender during school or worked in a grocery store or mowing lawns or something, or even in your uncle's small business on the weekends, you wouldn't include that in the online app dataset (though sometimes people do still include that stuff on the resume to show that they worked their way through school).

So you should look carefully at the instructions each school provides in their application. If you worked at one company but were promoted, then you should break that out as two separate jobs. If you worked at the same company as an intern for two summers, again, break it out as two separate jobs.

It's fine if you just have two jobs out of four slots though; it's not necessary to fill up all the sections -- in fact, it could make it appear that you're a job-hopper if you had too many in too short a time!!

The online app dataset should match the resume, they should complement each other, though as stated above, in some cases the resume might be more detailed (but those are exceptions - in most cases you'd want them to be the same).

HTH!
EssaySnark