What is the difference of cutoff frequency to -3dB frequency in an active filter?
I mean, isn't the cutoff frequency pertains to the -3dB frequency?

To some degree you are correct, but this article points out that simple rules do not apply to under-dampening (peaking) or over-dampening, they will make those 2 values not equal.
This is from Wikipedia

In electronics, cutoff frequency or corner frequency is the frequency
either above or below which the power output of a circuit, such as a
line, amplifier, or electronic filter has fallen to a given proportion
of the power in the passband. Most frequently this proportion is one
half the passband power, also referred to as the 3 dB point since a
fall of 3 dB corresponds approximately to half power. As a voltage
ratio this is a fall to \${\displaystyle \scriptstyle {\sqrt {1/2}}\
&gt; \approx \ 0.707}\scriptstyle\$ of the
passband voltage. Other ratios besides the 3 dB point may also be
relevant.


Chebyshev filters
Sometimes other ratios are more convenient than the 3 dB point. For
instance, in the case of the Chebyshev filter it is usual to define
the cutoff frequency as the point after the last peak in the frequency
response at which the level has fallen to the design value of the
passband ripple. The amount of ripple in this class of filter can be
set by the designer to any desired value, hence the ratio used could
be any value.