The implementations of the Gaussian smoothing is done quite differently. The Gaussian interpolator uses a N-D weighted region to perform the convolution. This is similar to the DiscreteGaussianImageFilter, which has a similar a
MaximumKernelWidth. The convolution will be done with N separated 1-D kernels.
The recursive Gaussian filters use a… recursive algorithm which does a 1-D forward processed to imaginary space, and a backwards processing step. The result is closer to “infinite” support of an approximation to a Gaussian. The doxygen has some links to some papers, but you may find other interesting reads about recursive Gaussian implementations other places.
Here is another recursive implementation available as a remote module: http://www.insight-journal.org/browse/publication/896
To answer your questions: no.