There are 5 different opening mechanisms for tonneau covers depending on their designs.
Snap tonneau covers
These covers are the most affordable option. However, they are the slowest to open and close since everything is done manually.
For you to open these covers, you are compelled to walk around to undo all buttons and then collect the tonneau cover to fold it up and secure it to the back of your cab with Velcro straps.
Roll-up or folding tonneau cover
Roll-up or folding tonneau cover are much easier to open than snap tonneau covers. Interestingly the names of these covers perfectly describe their opening mechanism.
Roll-up covers roll up towards the cab, and folding tonneau covers folds into three or four panels that later open.
The main disadvantage to a folding cover is that the panels fold on top of each other, taking a lot of space even when they are completely open.
Hinged Tonneau Covers
This tonneau covers open like a hood and is stiff making cleaning very easy. If you have installed this cover, you will be limited in some of the things you can carry since it still consumes some space when open. For you to gain full access to the bed you will have to entirely uninstall the tonneau cover.
If you frequently haul loads that must stick out of the bed and requires all time accessibility, you should try to avoid hinged covers. Instead, you should opt for either the snap or rolling covers.
Almost all folding tonneau covers give almost full accessibility depending on what you are carrying.
Retractable Tonneau Covers
This is another type of tonneau covers that gives full accessibility to your truck bed. They are also the quickest to open and close because they slide into a canister that is installed in the truck.
Retractable tonneau covers come either operated manually or using an electric motor. If you are looking for a hands-free tonneau cover, then the automatic version of this tonneau cover should be your top choice.