I've noticed a very small yet perceptible difference between the title pages I produce and some that I've stumbled across.
Using the standard
\maketitle command and filling in the standard author, date, abstract fields, I produce something that looks like
However, I've come across many papers with titles that look more like this.
You'll notice that in the latter case, the kerning is a bit smaller and the font seems a bit thicker. However, the font isn't bold (I tried that) and I've seen this often enough that I'm quite sure it's not a manual kerning or font weight edit, but rather just a command or package I'm not aware of.