  The repeating FRB 121102 (the "repeater") shows {repetitive bursting
activities} and was localized in a host galaxy at $z=0.193$. On the other hand,
despite dozens of hours of telescope time spent on follow-up observations, no
other FRBs have been observed to repeat. Yet, it has been speculated that the
repeater is the prototype of FRBs, and that other FRBs should show similar
repeating patterns. Using the published data, we compare the repeater with
other FRBs in the observed time interval ($\Delta t$) - flux ratio ($S_i /
S_{i+1}$) plane. We find that whereas other FRBs occupy the upper (large $S_i /
S_{i+1}$) and right (large $\Delta t$) regions of the plane due to the
non-detections of other bursts, some of the repeater bursts fall into the
lower-left region of the plot (short interval and small flux ratio) excluded by
the non-detection data of other FRBs. The trend also exists even if one only
selects those bursts detectable by the Parkes radio telescope. If other FRBs
were similar to the repeater, our simulations suggest that the probability that
none of them have been detected to repeat with the current searches would be
$\sim (10^{-4}-10^{-3})$. We suggest that the repeater is not representative of
the entire FRB population and that there is strong evidence of more than one
population of FRBs.
