= Structural formula
A \b[structural formula] represents how <chemical atoms> in a <molecule> are connected. It adds information that a <molecular formula> alone does not provide. Depending on the notation, bonds and grouped atoms may be drawn explicitly or represented in a <condensed structural formula>.<IUPAC Compendium of Chemical Terminology, fifth edition (Gold Book) by International Union of Pure and Applied Chemistry>[Entry S06061, structural formula: information about atom connectivity; DOI10.1351/goldbook.S06061.]{ref}
For <ethanol>, $\mathrm{CH_3CH_2OH}$ can be unpacked as a carbon with three hydrogens, joined to a carbon with two hydrogens, joined to oxygen, joined to hydrogen. Counting the groups recovers $\mathrm{C_2H_6O}$, since $3+2+1=6$. That count is a useful check, but it discards the connectivity information that distinguishes <ethanol> from <dimethyl ether>, $\mathrm{CH_3OCH_3}$.
A structural drawing also needs a clear convention about spatial meaning. A plain line usually represents a <chemical bond>, rather than a measured length on the page. Rotating the paper does not change the represented <molecule>. If a drawing is intended to specify a three-dimensional configuration, the additional conventions belong to <stereochemistry>; a connectivity formula should not silently be treated as complete <molecular geometry>.
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