What is Lighter vs. What is Heavier: Understanding the Difference

Both "What is lighter?" and "What is heavier?" are grammatically correct, but they convey different meanings.

"What is lighter?" implies that there is something that is being compared to determine which one is lighter. For example, if you were comparing two objects, you might ask "What is lighter, this object or that object?"

On the other hand, "What is heavier?" implies that there is a known object or reference point that is being used as a basis for comparison. For example, if you were comparing two objects and wanted to know which one was heavier, you might ask "What is heavier, this object or that object?"

So, in summary, "What is lighter?" is used when you are comparing two unknown objects, while "What is heavier?" is used when you have a known reference point for comparison.