Here's why:

* Methane (CH₄): Methane is a simple hydrocarbon consisting of one carbon atom bonded to four hydrogen atoms.

* Methyl Isocyanate (CH₃NCO): Methyl isocyanate contains a methyl group (CH₃) but also has a nitrogen atom and an oxygen atom.

While it has a methyl group, the presence of nitrogen and oxygen makes it a distinct compound from methane.