  This paper compares and contrasts the emission of two high nulling fraction
pulsars, PSRs J1738-2330 and J1752+2359. In both pulsars the emission bursts
appear in a quasi-periodic fashion with typical separations of several hundred
pulses, and in J1738-2330 there is evidence of two underlying periodicities
with memory persisting for at least 11 bursts. By contrast, in J1752+2359 the
pattern coherence is rapidly lost and the burst/null lengths appear to be
selected randomly from their respective quasi-normal distributions. The typical
emission bursts of J1738-2330 exhibit a steady exponential decay of on-pulse
energy accompanied by a flickering emission characterized by short frequent
nulls towards their end. In the bursts of J1752+2359 the flickering is absent,
the decay more pronounced and the energy released during each bright phase is
approximately constant. Unlike J1738-2330, the average profiles for the first
and the last pulses of J1752+2359 bursts differ slightly from the pulsar's
overall profile, hinting at differences between the two pulsars in their
transitions from null to burst state (and vice-versa). During its long null
phases, J1752+2359 is found to emit random weak inter-burst pulses (IBPs) whose
profile peak is somewhat offset with respect to the overall average profile.
Such pulses have no equivalent in J1738-2330 or in any known pulsar hitherto.
They may pervade the entire emission of this pulsar and have a separate
physical origin to normal pulses. On the basis of our comparison we conclude
that a pulsar's nulling fraction, even when high, remains a poor guide to its
detailed subpulse behaviour, as previously found for pulsars with small nulling
fractions.
