For the most part you can think of library science as just another name for the body of knowledge and principles that are the basis of being a librarian. The best reason I’ve been able to come up with for librarians needing six years of tertiary education is that highly educated librarians have been found, through experience, to add more value to the enterprise than a mere filing clerk for books would. One reason is that uneducated staff would be less able to communicate with the patrons effectively and understand their research needs. Besides reference services, librarians deal with collection management (adding and dropping items), community or campus outreach to better understand and serve their patron base, and cataloging. Much cataloging work is routine, and national standards do exist, but it often happens that a library decides to adapt these to their own use.
One does not need to know anything about programming to be a Help Desk Technician, as a general rule. The primary skilled trade of programmers would be programming, as an example, the programmers that I work with generate or adapt existing code, among other things. Help desk technicians usually work with existing operating systems and applications and provide first level support on those. That said, it’s not uncommon for persons with one of these skill sets to also possess the other.