The Tiago Pinto Caricatures are faces made solely of different letters and symbols from a single font. These quirky characters look widely different according to the type that they are comprised of.
University professors and high school teachers stress the importance of Times New Roman or Arial type for all essays and assignments for professionalism sake; the same is said for resumes. So it is common knowledge that a font has the ability to easily change the tone of any piece of writing -- just take the Higgs-Boson discovery presentation in Comic Sans fiasco for example.
It is clear that this is the case with faces too; their personalities range from baby cute to goofy to sophisticated to studious. The range in expression is endless!