[rajandatta]

Yes - Concatenation Languages and stack-based languages refer to the same paradigm and group of languages. Forth is the original and oldest. I've looked at Factor and it's a really impressive piece of work. Well worth studying.

[zsyllepsis]

I don’t think this is accurate. While most popular concatenative languages are stack-based, that is not a requirement for the paradigm. The Wikipedia article calls out a few alternatives, such as Om.

Source: https://en.m.wikipedia.org/wiki/Concatenative_programming_la...

[pxeger1]

APL-family languages are somewhat concatenative but not stack-based. They use grouping rules to form chains of composed functions.