I don't think the stack in a traditional languages is the same as stacks in stack machines and languages. It's a lump of memory that gets allocated to a thread for stuff, and the allocation is indeed done in LIFO fashion, but I believe access to individual memory locations in the allocation is random. Name is the same, LIFO and all, but the mechanism granularity makes it quite different.
It is true that traditional languages lump local variables and return information in the same stack. But the difference is only in the way this is handled by the program. In traditional languages the programmer has no idea how parameters are passed in the stack and the compiler does everything. In Forth this is made explicit, but on the other hand there are no formal parameters to worry about (notice that Forth can use local variables if you want, it is just not the idiomatic way).
