Each of the font formats have their strengths and weaknesses, and I chose to offer the two most versatile formats for foreign language texts. And I chose not to offer both formats in the same download, as that would inevitably end up with users installing both formats of the same font - and that would lead to all sorts of conflicts for them...
So check out the format information before you decide on a format (or purchase both, but don't install them both on the same machine ;)