IT Technology: Difference between OTF (Open Type) and TTF (True Type) Font Formats

OTF is more likely to be a “better” font, as it supports more advanced typesetting features (smallcaps, alternates, ligatures and so on actually inside the font rather than in fiddly separate expert set fonts). It can also contain either spline (TTF-style) or Bezier (PostScript Type 1-style) curves, so hopefully you're getting the shapes the font was originally designed in and not a potentially-poorer-quality conversion.

On the other hand, if you're downloading free fonts from shovelware sites, you're unlikely to get any of that. Indeed, you may simple be getting a TTF font renamed to OTF.