Just to reinforce this post: Icebreakers hit ice fields (not icebergs, more on that later) head-on, the Titanic hit the iceberg from the side/diagonally (think of an empty soda/beer can, is it easier to crush from the sides or the top/bottom?)

Secondly, as I said before, icebreakers are meant for ice fields, not icebergs. What is the difference, you might ask? Ice fields are less compact, which means that the icebreaker can push the ice around without as much pressure being applied to the hull (think of a full soda/beer can, it is much harder to crush than an empty one. The ice field has room to buckle, much like an empty can, where as the iceberg has no room to buckle, much like a full soda/beer can). If an icebreaker were to take on an iceberg, the icebreaker would be damaged. The extent of the damage depends on the size of the iceberg.