All lies are deceptions, but not all deceptions are lies
Lies are specific acts that are done, not acting is in itself not an act
Conservation of energy cannot be called an expenditure of energy
When people call something a "lie by omission" it's an attempt to shift the blame wholly to the other person rather than deal with the fact that part of the blame belongs to themselves
My silence was not a lie; you guessed about reality, and I just didn't correct you
You can still use it as a basis for future distrust and you can still use it as a reason to cut off or minimize future encounters
But it is not and should not be considered a malicious action against you as you would a lie