A real ripper is a very big farm tool, it will cover 100's of acres in a day, it breaks up deep compaction and lets water and air infiltrate heavier soils. It leaves the ground very rough.
A tiller is an all in one tool for small areas, it only goes a few inches deep but it creates a good garden seed bed. It takes too much power & pulverizes the ground too much for a big farm field, but is ideal as the 'one' tool to get most any ground into a good plantable seedbed.
A disk is a secondary tillage tool, it will cut up and level out rough ground, like after it is plowed. It smooths out plowed or chiseled or ripped ground. It does tend to pack clay type soils and is rarely used in my area any more.
A plow is a primary tillage tool like a ripper or chisel plow, it turns the ground over & leaves it rough.
A field cultivator is like a disk as it does secondary tillage, leveling off rough ground. It works well in clay soils, where you want to lift and dry the soil, not pack it down hard like a disk does.
A ripper or chisel plow has big heavy shanks that go deep. A chisel plow has lighter, shallower, closer together shanks, tho they both look 'kinda the same' from a distance.
A drag or harrow is a finishing tool, it will drag the ground very level and smooth, bust up small clods.
Many times a harrow is added on to the boack of a field cultivator or disk to do both jobs at one time.
So, to rip up sod or tough crop cover and hard packed ground, you use a ripper, chisel plow, or molboard plow. Goes 8 to 15 inches deep.
To work up soft ground, already worked ground, you use a disk or field cultivator. Goes 4-5 inches deep.
To really finish off the ground smooth, you use a harrow or drag. Goes an inch or 2 deep.
A tiller is a whole different thing, it pulverizes the soil but typically only goes a few inches deep and struggles with heavy crop residues or sod. It's a good one-pass option to turn almost any ground into a smooth fine seedbed, but it takes a few passes to work up sod and it doesn't go deep enough to break up deeper compation.
In my clay soil, a molboard plow in fall, with a field cultivator and harrow pass in spring, works up the ground the best. A tiller would work up a garden real well if you don't have it compacted.
--->Paul