Q: Is there more than one type of canister adaptor?
Yes. There are two different attachment fittings. The vast majority (including all US manufactures) of canister stoves use the EN417 Lindal valve, while in Europe,
several use the Camping Gaz canisters which are very similar except that the valve is smooth instead of threaded like the Lindal valve. At least one stove, the MSR Superfly, will work with either
type of fitting.
In the US, the Lindal fitting is by far the most common. In fact, it is difficult to even find canisters for the Camping Gas fitting.
See BackpackingLight.com's Canister Stove
FAQ for details.