  We study thermodynamics of the four-dimensional Kerr-Sen-AdS black hole and
its ultra-spinning counterpart, and verify that both black holes fullfil the
first law and Bekenstein-Smarr mass formulae of black hole thermodynamics.
Furthermore, we derive new Christodoulou-Ruffini-like squared-mass formulae for
the usual and ultra-spinning Kerr-Sen-AdS$_4$ solutions. We show that this
ultra-spinning Kerr-Sen-AdS$_4$ black hole does not always violate the Reverse
Isoperimetric Inequality (RII) since the value of the isoperimetric ratio can
be larger/smaller than, or equal to unity, depending upon where the solution
parameters lie in the parameters space. This property is obviously different
from that of the Kerr-Newman-AdS$_4$ super-entropic black hole, which always
strictly violates the RII, although both of them have some similar properties
in other aspects, such as horizon geometry and conformal boundary. In addition,
it is found that while there exists the same lower bound on mass ($m_e
\geqslant 8l/\sqrt{27}$ with $l$ being the cosmological scale) both for the
extremal ultra-spinning Kerr-Sen-AdS$_4$ black hole and for the extremal
super-entropic Kerr-Newman-AdS$_4$ case, the former has a maximal horizon
radius: $r_{\rm\, HP} = l/\sqrt{3}$ which is the minimum of the latter.
Therefore, these two different kinds of four-dimensional ultra-spinning charged
AdS black holes exhibit some significant physical differences .
