I grew up on a farm but left it 50 years ago. So, some of my information may be kinda out of date.
Nowadays, a lot of farmers are going to no-till agriculture. One way to do your trees is to use a brush hog to cut stuff down to a low level, maybe in a couple passes if it's really nasty: once cutting maybe 4-6" high, walk all over it to locate problems and fix and then cut low maybe 2-3". Then use Roundup to kill all the vegetation. Then just dig your tree holes with a big diameter post hole digger.
The old way of tilling ground was to plow with a rotary disc (hugh, about 2' diameter) or "moldboard" type plows. The ground will be VERY rough because of the big furrows made by the plow. So, farmers often let it sit a spell to let nature even it out a bit before going over it with a huge "disc" made up of multiple small discs, maybe with a harrow being pulled along behind the disc to totally even it out. A harrow is kinda like a hand rake with with fewer teeth/foot or inch, mainly just a metal frame with some spikes in it. Some use an ole piece of fencing or something similar.
A cultivator is usually used to tear up dirt between rows to eliminate weeds with the tractor. The idea is to very lightly go underneath the soil layer to cut the weeds but not to expose much new dirt that has more weed seeds. These usually have multiple little "plows" that run between the rows. One has to steer the tractor very well to avoid going into the rows and cutting up the crop. The little plows also throw some dirt up onto the row and against the crop to cover any weeds there.
There are some "cultivators" (and I've got one) that have skinny plows on them that are used to tear up the soil for next year's crop. Think use of these aren't in line with the idea of no till, because they'll bring some new soil to the surface and expose weed seeds. Also, they'll tear up micro pores made by worms and other microbes that you want to retain.
I use the framework for my cultivator plows to mount a couple big discs opposed 45 degrees and running behind the tractor's tires to maintain the raised rows in my veggie garden, not actually touching the rows. These are called disc hillers. Some disc hillers have the disc plus something like a tiller in between them to really tear up the dirt. This, again, doesn't fit with new "no till" technology.
Of course, there are rotary tillers that do the job of the old plow, disc and harrow. These, again, don't fit with the new "no till" technology.
Ralph