According to the LEGO site, "The IR Receiver V2 version has an improved motor driver giving you lower power loss and longer battery lifetime".
However, according to a popular conspiracy theory, this is the same part as the previous one, just more expensive.
Element ID is actually Dark Bluish Gray.
Click on a colored part below to see the Sets and MOCs that use part 58123b Electric Power Functions IR Receiver with V2 Print in that color. You can find an overview of all LEGO Colors here.
If a color is missing, it probably needs to be added to a Set Inventory.
This part has been used by MOCs in the following colors but not officially released.