Kernel Density Estimation using scipy's gaussian_kde and sklearn's KernelDensity leads to different results

What is meant by bandwidth in scipy.stats.gaussian_kde and sklearn.neighbors.KernelDensity is not the same. Scipy.stats.gaussian_kde uses a bandwidth factor https://docs.scipy.org/doc/scipy/reference/generated/scipy.stats.gaussian_kde.html. For a 1-D kernel density estimation the following formula is applied:

the bandwidth of sklearn.neighbors.KernelDensity = bandwidth factor of the scipy.stats.gaussian_kde * standard deviation of the sample

For your estimation this probably means that your standard deviation equals 4.

I would like to refer to Getting bandwidth used by SciPy's gaussian_kde function for more information.