What is the difference between denaturing and non-denaturing (native) gels?

Denaturing gels are run under the condition that disrupts the natural structure of DNA/RNA or protein, which are unfolded into liner chains. The speed of these macromolecules moving through a gel depends only on their linear length and the mass-to-charge ratio; thus, only the primary structure is analyzed. Urea is usually to denature DNA or RNA, while sodium dodecyl sulfate is used for protein denaturing.

Non-denaturing (native) gel, on the contrary, are run under conditions that no disruption of structure is introduced to analytes. In this case, the cross-sectional area of the macromolecule, in addition to the molecular mass and intrinsic charge, is also a factor for gel separation, allowing for analysis of all four levels (primary, secondary, tertiary, and quaternary levels) of the biomolecular structure.