From the bench, the distinction that matters is only one: there are systems that use standard spring bars with an added release mechanism, and systems that require a proprietary interface. Confusing them leads to wrong purchasing choices and, sometimes, to scratched cases.
The principle is simple. In traditional straps, the spring bar — the spring pin — is compressed with a dedicated tool. A quick-release system introduces a supplementary element: a tab, a lateral button, or a bayonet mechanism that compresses the spring bar from the outside, without tools. The practical result is that changing the strap becomes a matter of seconds.
Manufacturers have taken different paths. Panerai uses the Click Release System, Hublot the One Click, IWC the EasX-CHANGE, Cartier the QuickSwitch on the Santos: four proprietary solutions, four different lug architectures. This means that a strap designed for one system is not interchangeable with another, even when the nominal width matches. It's the point that generalist sellers tend to keep quiet about.
There are also hybrid solutions. The Straum Jan Mayen, to cite a lesser-known case, uses a proprietary interface visually integrated into the mid-case but still mounts standard spring bars inside: those with patience and tools can exit the brand's ecosystem. The Omega Dynamic from the Seventies-Eighties, on the other hand, adopted a retaining ring screwed onto the caseback — technically not a quick-release, but the first attempt to make strap-bracelet changes domestic without resorting to a watchmaker.
Bayonet quick-release systems — small spring tabs integrated directly into the spring bar — are the most widespread solution on the independent and aftermarket. They work well when the lugs leave enough space for fingers; on the Tissot PRX, for example, the space between caseback and lug is so tight that the practical advantage is almost entirely nullified.
A separate variant is the keeperless system, which eliminates the retaining slot for the free end. It doesn't concern the release from the case, but the strap geometry itself: it reduces total thickness and changes how it sits on the wrist. You find it on some limited production watches, MING among them.
From a conservation standpoint, proprietary systems create dependence on the brand's ecosystem for spare parts and accessories. Worth keeping in mind before purchasing.