Both spirits are distilled from agave plants, but tequila can
only be distilled from certain agave plants. In order for a
spirit to be legally advertised as tequila, it must be made from
the Weber blue agave, and grown in specific territories
recognized by the General Declaration on the Protection of the
Appellation of Origin Tequila, as put forth by Mexico’s Tequila
Regulatory Council.
Anything else made from the agave plant – even to near-identical
standards – is a mezcal, which is technically a blanket term for
any spirit distilled from agave.
Agave hearts, or piñas used in the production of either tequila
or mezcal can be cooked before fermentation, though those used
for mezcal are more often roasted in underground pits, imparting
the finished product with generally more of a smokier aroma and
taste.
Following the
fermentation and distillation processes, tequilas and mezcals
can be aged to varying degrees before bottling, resulting in
multiple distinctions. The distinctions include Blanco (bottled
within two months), Reposado (aged between two and 12 months)
and Añejo (aged longer than 12 months), with the younger
tequilas generally being better for mixing, and the older better
for sipping.
All tequila is mezcal,
but not all mezcal is tequila.
Incidentally, Mezcal
is Spanish and mescal is English spelling.