Infinite impulse response (IIR) filters 
IIR filters are digital filters with infinite impulse response, which have both poles and zeros. IIR filters typically meet a given set of specifications with a much lower filter order than a corresponding FIR filter. Therefore, generally IIR filters are more efficient in memory and computational requirements than FIR filters. A drawback of IIR filters is that they have non-linear phase responses.

Finite impulse response (FIR) filters 
FIR filters are also known as convolution filters, or moving-average filters because the output values of an FIR filter are described as a finite convolution. FIR filters have only zeros (no poles). FIR filters can have linear phase characteristics, which are desirable in many applications.