HyperText is text which is not constrained to be linear.
HyperText is text which contains links to other texts.The term was coined by TedNelson around 1965 (see History).
HyperMedia is a term used for hypertext which is not constrained to be text:it can include graphics.video and sound,for example.Apparently TedNelsonwas the first to use this term too.
Hypertext and HyperMedia are concepts,not products.
see also: