The contents of the blocks of the Bitcoin blockchain (and other cryptocurrency blockchains) happen to be Merkle trees (of transactions, in Bitcoin's case). Blockchains as a data structure are unrelated to Merkle trees.
I legitimately don't understand what distinction you're trying to make here. Typically a "nit" clarifies something, but you're just muddying the discussion for seemingly no real benefit.
It is a basically set of Merkle trees, each with a header.