What's the differenct between series peaking and shunt peaki

series and shunt peaking are generally used to extend the bandwidth of amplifer.

The topology of these two structure looks so similar that I can't tell the difference.

Who knows?

seriels peaking is serielly connected in signal pass
while shunt peaking is parallelly connected and signal will not pass through it.
for detail, you can reference the book writen by Tomas Lee( The Design of CMOS Radio Frequency Integrated Circuit)
the chapter high frequency Amplifier design