Difference between these frequency response curves
The two frequency response plots are the result of two different models. In the first one, the model is a mass-spring-damper system as shown here, and the plot shows the ratio of the amplitudes of mass displacement and driving force.

The second plot shows the transmissibility of a single DOF mechanical system as shown below:



(from Fundamentals of Mechanical Vibrations by S.G.Kelly).

Note that here, unlike in the other model, the support is not fixed. The transmissibility shown in your second plot is the ratio of the amplitudes of the mass displacement $x(t)$ and the (forced) displacement of the support $y(t)$.

In formulas, your first plot shows the function

$$M(\omega)=\frac{1}{\sqrt{\left(1-\left(\frac{\omega}{\omega_0}\right)^2\right)^2+\left(2\zeta\frac{\omega}{\omega_0}\right)^2}}\tag{1}$$

where $\omega_0$ is the system's natural frequency, and $\zeta$ is the damping ratio. In electrical engineering terms, this is the magnitude of the frequency response of a second-order low pass filter.

The second plot shows the transmissibility given by Eq. (3.73) in Kelly's book:

$$T(\omega)=\sqrt{\frac{1+\left(2\zeta\frac{\omega}{\omega_0}\right)^2}{{\left(1-\left(\frac{\omega}{\omega_0}\right)^2\right)^2+\left(2\zeta\frac{\omega}{\omega_0}\right)^2}}}\tag{2}$$

Note that $(1)$ and $(2)$ have the same denominator but different numerators.