Embedding the fonts
If font embedding is enabled, Acrobat Distiller embeds TrueType and Type 3 fonts, and Type 1 fonts that don't use the ISO Latin 1 character set (such as symbol or expert characters). Acrobat Distiller 7.0 can embed OpenType fonts; however, the application that created the original document determines which OpenType font characteristics can be embedded. If you embed an OpenType font that is based on a Type 1 font, Acrobat Distiller embeds it as a CFF/Type 2 font. Acrobat Distiller embeds Open Type fonts that are based on TrueType fonts as TrueType fonts.
A font that is embedded in a PDF file is always available for viewing and printing, whether or not it's installed on the system. However, you cannot edit text in the PDF file unless the font is installed. If you try to edit text that uses an embedded font and the font isn't installed, Acrobat returns a warning and uses a substitute font instead.
Font permissions
Acrobat Distiller acknowledges and preserves the original font permissions, even if a PDF file is redistilled. Fonts that have restricted permissions can't be embedded and will cause Acrobat Distiller to return an error during the conversion process. Similarly, fonts that don't use a character encoding format, such as WinAnsi or MacRoman, may cause Acrobat Distiller to return an error if you try to embed them.
Converting the fonts
If Acrobat Distiller can't interpret or find the font information it needs from a font, it substitutes the font. In rare instances, Acrobat Distiller converts such fonts to bitmap images, which prevents the font from being searched, scaled, or edited. Acrobat Distiller typically converts PCL fonts and Windows vector (outline) fonts to bitmap images. See the "How Postscript Printer Drivers Handle TrueType Fonts in Windows" section in this document.
http://www.adobe.com/support/techdocs/325165.html