Tubes & Bellows
Both tubes and bellows serve the same purpose, to add a spacer between the camera lens and the camera body. This allows any lens to focus closer without the need for a close up lens to be fitted.
Both can be manual, or automatic, but the amount of facilities available through the automatic link varies between models. The automatic features include operating the aperture ring allowing you to focus and set up the shot with the aperture fully open and then closing down the lens when the image is taken, as you do when normally using any lens, to fully passing through or auto focus and other electronic controls and information.
Tubes are fixed sized sections can be purchased, in some cases, individually but often come in sets of varying thicknesses. You can add together different sections, allowing a range of size options.
Bellows are expandable within a range, starting at a point equal to several tubes and going to a far larger length. Bellow extensions can be obtained taking it to an even further length. You will find that the shape of most cameras involving a protruding section to hold, means that bellows are too bulky to directly fit onto the camera, but you need at least one tube first to have enough working room.
Usually bellows are far more expensive to purchase than tubes.
As neither have any glass or lenses there is no quality difference in the resulting photographs by using different makes.
I would use a macro lens to get to 1 to 1, perhaps allowing something the size of a grasshopper to be viewed full frame, then use tubes to get closer, perhaps to the point where I could photograph a bees head full frame. Another comparison is, if we look at the word Nikon on a lens cap, then the Nikon word is just about frame width with the macro at 1:1, while with the full set of tubes the frame width is just 2 out of the 5 letters.
To get closer I then may take of some tubes, leaving just one and connect up the bellows to this, expanding this out as far as I need it, adding or removing tubes to give me a greater range.
Tubes, Bellows and Reversing Ring in use