Interpolation vs Interpolation Filter?
Interpolation is the process of adding zeros in between your samples and then low-pass filtering to get rid of the aliases that result.  Linear interpolation is just one out of many different possible filters.  Linear interpolation filters can always be represented by FIR filters.  In one-dimension the interpolation by two linear interpolation filter is $[\frac{1}{2}, 1, \frac{1}{2}]$.  There are better low-pass filters.

It is not clear from your quote what they meant by a "wider" filter.  I'm guessing they mean "one with more taps", but it could also mean "one with a wider passband".