Manufacture is a term you'll see bandied about in high-end Swiss watches quite a lot; it's supposed to mean a company that makes its own movements.
From the comprehensive Montres page
Thus, "manufacture" without a doubt is a "Term of Art" in the Swiss watch making industry. It is applied on two levels: first to a maker who has the "capacity" to construct a watch movement in its own factory and; second to a movement, so constructed.
Note that 'manufacture' is often BS. It carries prestige and price and is therefore suspect. E.g. Hublot claiming the 7750 as an 'in-house' movement.
Seiko is a manufacture. No one else makes everything. Many others make less but still claim the title.