The difference is that liberals "object" but don't support or promote bans. Liberals may go so far as to use the already existing library mechanisms that allow parents to oversee and control what materials their children may access.

For example, my son was a very early reader. I didn't want him to read Mark Twain at the tender age of six or seven – which he was totally able to do; he was reading on fifth grade level by the time he reached second grade. He brought home Treasure Island from the school library. He was also given The Adventures of Tom Sawyer and The Adventures of Huckleberry Finn by someone; I put them away until he was older. As for the library, I returned the book and filled out the form requesting parental authorization before he checked out anything. I didn't want him reading those books at that age, not because I objected to the content, but because at such a level of emotional and socio-cultural development I did not believe my son was able to contextualize and understand the content.

After he moved on to middle school, I made no such restrictions on his reading materials.