  Critical end points and tricritical points are multicritical points that
separate lines of continuous transitions from lines of first order transitions
in the phase diagram of many systems. In models like the spin-1 disordered
Blume-Capel model and the repulsive Blume-Emery-Griffiths model, the
tricritical point splits into a critical end point and a bicritical end point
with an increase in disorder and repulsive coupling strength respectively. In
order to make a distinction between these two multicritical points, we
investigate and contrast the behaviour of the first order phase boundary and
the co-existence diameter around them.
