2. Professionally typeset and format papers to thousands of styles in one click

tl;dr In Overleaf you start with a template -- in Authorea you write without thinking about format and then export to the style you need
A benefit of LaTeX is that it outputs beautifully typeset PDFs. Overleaf accomplishes this in the traditional way: you write LaTeX in a template and then compile a PDF using that template styling. Authorea, in comparison, separates format from content. Content is not restricted by a particular output format. At any time, you can export a PDF, Word, or LaTeX version of your document in the style of your choice. For example, your requirements may look like this: "download a one column line-numbered 12pt version with APA citations and figures positioned at the end of the document". Why is this important? If Journal X rejects your manuscript, you won’t waste a day reformatting it for Journal Y. Authorea does it in one click. (And yes, you can also easily export your LaTeX papers to Word's .docx format!)