The HTML fonts are controlled by font files on the user's computer. The PDF fonts are controlled by the fonts that are in the web site's font selection, and should look the same on any computer that can display PDF output.
The Gallaude ASL (sign language font) is from: http://lifeprint.com/asl101/pages-layout/gallaudettruetypefont.htm. Please read their page for information. As we don't control the fonts you have installed on your computer, this choice is only available for PDF. See: http://en.wikipedia.org/wiki/Fingerspelling for information regarding finger spelling.
The British Sign Language font is from: http://www.xrmx.com/wisdom/signs-n-symbols/signing/. This is a two handed sign language used in Great Britain. Again, we don't control the fonts on your computer, so this option is only available for PDF.