An account is something you have at the iTunes Store. A library is a collection of things in iTunes on your computer.
You probably do not want them syncing to your library directly. They will definitely see your playlists and can add and delete items. There's ways to limit this but without going into the half dozen ways of doing things I still think Family Sharing may be best unless you are trying to wean the children off your iTunes Store account and onto their own accounts.
With family Sharing they don't see what is on your iPhone, they only see available items purchased from Apple within the shared group, and as permitted.
Family Sharing - http://support.apple.com/kb/HT201060 - "Content can be hidden by family members; hidden content is not available for download."
Note it says "purchased" as in purchased from Apple. If you intend to share media from CDs and other sources you will probably have to set up alternative sharing such as Home Sharing where each person syncs to their own iTunes library but items can be shared locally.
iTunes: How to share music and video - http://support.apple.com/kb/HT2688 - about Music Sharing and Home Sharing
Home Sharing Support page - http://www.apple.com/support/homesharing/
iTunes 12 for Mac: Use Home Sharing to import items from another iTunes library - https://support.apple.com/kb/PH19614
iTunes: Setting up Home Sharing on your computer - http://support.apple.com/kb/HT4620
Understanding Home Sharing - http://support.apple.com/kb/HT3819