Is this kernel name as mean difference kernel or Laplacian filter?
Is mean difference just a method?
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There are many approximations for the Laplacian Filter (See The Hypermedia Image Processing Reference - Laplacian/Laplacian of Gaussian):
Indeed this is an High Pass Filter (HPF). Namely it will remove (attenuate) low frequencies (Specifically it will remove the DC Value, namely the output image will have mean value of 0).