  Quintessence, a scalar field model, has been proposed to account for the
acceleration of the Universe at present. We discuss how accurately quintessence
models are discriminated by future cosmological surveys, which include
experiments of CMB, galaxy clustering, weak lensing, and the type Ia SNe
surveys, by making use of the conventional parameterized dark energy models. We
can see clear differences between the thawing and the freezing quintessence
models at more than $1\sigma$ ($2\sigma$) confidence level as long as the
present equation of state for quintessence is away from $-1$ as $w_X \gtrsim
-0.95 (-0.90)$. However, it is found to be difficult to probe the effective
mass squared for the potential in thawing models, whose signs are different
between the quadratic and the cosine-type potentials. This fact may require us
to invent a new estimator to distinguish quintessence models beyond the thawing
and the freezing ones.
