Methane vs. hydrogen, etc.

Excuse me, but I don't understand how you can have more hydrogen in one
cubic meter of liquid methane than in one cubic meter of liquid hydrogen.
Just how is this accomplished, or did I miss something in Chemistry class?
In one meter cubed of LH2, it's ALL hydrogen, right?  Now in one meter cubed
of NH3, it's not all hydrogen, but some of the space is taken up by nitrogen
atoms.  So how can you save space by carrying methane, or anything else?

Hmmm?

Chris