Chemical engineering is more about running large-scale chemical reactions while materials science is about studying specific properties of materials. A chemical engineer may be tasked with designing a reactor that runs continuously to produce some polymer while a materials scientist would be tasked with figuring out why the polymer, in its final form, acts the way it does.
In modern curricula, it seems to me that chemical engineers are essentially applied organic chemists while materials scientists are essentially applied condensed matter physicists.
Of course there are always exceptions and overlaps. Hope this helped.