Basicly, when finding a block scanner its identified as 'plethora:scanner' but the item name in the inventory is called 'plethora:module_scanner' which makes it harder to equip it and use the same name to peripheral.find it.

I see that you resolved your differences with this difference in-game. For future reference, you can use the peripherals program to get valid peripheral names.

For a neural interface, the peripheral is neuralInterface:

For a manipulator, the peripheral is manipulator:

For a turtle, the peripheral is the module name as shown in .listModules():

I agree that this difference is a little confusing, but it would likely be a breaking change to do anything about it now.