OpenType is a cross-platform font format developed by Adobe and Microsoft in the late 1990s. It has the faculty to include an expanded character set and layout features to provide richer linguistic support and/or advanced typographic control such as various numeral styles, ligatures, small capitals and contextual substitutions.
OpenType supports Unicode, which enables the fonts to contain more than 65,000 glyphs while ʻPostScript®ʼ fonts are technically limited to a maximum of only 256 characters. This means that a user does not need to have separate fonts for Western, Central European or other languages, but could have one single file which supports all these encodings.
OpenType fonts, as a new industry standard, will work in all applications, however only some applications take profit of the advanced OpenType features, other applications will only use the first 256 characters.