Can someone please explain to me the difference between a stylistic alternate and a titling alternate? When I look at a font that includes these I can clearly see a difference so I guess I'm looking as to why they are designated as such and maybe a definition for each type? Also, what exactly is a discretionary ligature, as opposed to just a ligature? Thank you!

http://www.magnetstudio.com/2014/03/22/beginners-guide-to-opentype/

Perfect, thanks claudeserieux!