What are the similarities between academic and nonacademic texts?

It is much easier to say what academic and nonacademic texts do not have in common rather than their similarities, but I can say the following:

Both academic and nonacademic texts may be written with the goal to persuade, to entertain, or to inform. They differ in their approach to these goals, though, with academic texts relying far more on research and factual, verifiable material for their content. Nonacademic texts may also include research or verifiable material, but are less likely to include references to any source material, and may be published in a rather informal setting.

Academic and nonacademic texts are also typically written for a particular audience. While nonacademic texts are intended more for mass, public consumption than scholarly or academic texts, they may be targeted towards special interests or occupations in society. 

When it comes to format, both academic and nonacademic texts may be found in print, periodical, and digital forms.