Exactly. That's what I meant by "different product line," like how Honda makes both cars and motorcycles, they may share similar underlying concepts (e.g. combustion engines), but they're separate things entirely.
And since RISC-V is open source, the discussion about companies is irrelevant. AMD could make RISC-V chips if it wants, and they do make ARM chips. Same company, three different product lines. Intel also makes ARM chips, so the same is true for them.