I had to do a bit of testing. The find nearest command is very......weird. I may be wrong about how it functions (shocking), but this is my experience.
Move To (item): Same exact function as "Move To" command. The value is stored as an xy coordinate I presume.
Pick Up (item): This picks up an individual "item". The "item" is programmed by the find nearest command.
Here is where it goes down the rabbit hole.
Find Nearest (item): This command programs other commands below it in sequence. If you say to find nearest berry, move to mushroom, and pick up stick, it will move to berry and pick up berry. The sequence is very specific as well. If you have "find nearest" - "Repeat (closed so it will skip to next line)" - "Move To" - "Pick up" , it will move towards the ends of the earth and I do not know why. Flip the "Pick up" and "Move To" commands and now it will Pick up the specified item (not items plural unless repeatedly reprogrammed to find another item) and "Move To" where ever you specified the coordinate (i.e. not reliant on find nearest). To calrify, the "Move To" will retain its value unless programmed by "Find Nearest" while the "Pick Up" must be programmed to pick up anything. The location of "Pick up" to be programmed must at least be after "Find Nearest" in sequence while "Move to" must be directly after "Find Nearest" to be programmed. As to why the bot moves towards the edge of the map when a repeat (closed) is before a "Move To" is a mystery to me.
Denki, why did you make this so complicated :p
Edit: Also forgot to mention that "Find Nearest (item)" programs the "Move To (item)" based on the closest location of the "item" from the point of origin or where you told it to "Find Nearest". You can visibly see the point of origin as a red circle when you hover over the "Find Nearest" command. If you specified a beacon, it will find the closest item from the beacon and not the point of origin.