Rebol Technologies went bankrupt, and Rebol is de-facto dead since more than a decade; Red barely manages to get by thanks to a recent crypto spike.
> I would say the languages are very different in the sense that Beads is clearly aimed at graphical interactive software.
So is Red with it's native GUI engine. [1]
> Red exists as a systems programming language, a variant customized for building crypto contracts, and then as a general purpose language.
"Domain-specific languages" is the term you are looking for.
> They are so different that it is hard to compare.
Both share the same goal of replacing modern software practices with biased, batteries-included toolchain, varying only in implementation.
> Red being a concatenative language has more in common with FORTH than Algol.
Red is not concatenative in any sense of the word, nor any other language in Rebol family that I know of.