Substrate integrated waveguides (SIW) have attracted much attention in recent times. They present higher quality factor and lower losses for resonators than classical planar technologies, while maintaining low cost, easy manufacturing, small size, and integration with other circuits in the same substrate. Empty substrate integrated waveguides (ESIW) have appeared, decreasing losses by removing the SIW dielectric substrate, at the cost of increasing the circuit size. In this work, the same four-pole folded filter has been designed, manufactured and measured both in SIW and ESIW technologies, in order to compare the electrical response, losses and area occupied by each circuit, with the final aim of assessing the advantages and disadvantages of both technologies.