What's the difference between a two-speed and single-speed thickness planer?

A two-speed planer lets you switch between a faster feed rate for rapid stock removal and a slower feed rate that produces more cuts per inch and a smoother finish. Single-speed machines force you to choose lighter passes for a clean surface. Among these candidates the DEWALT DW735X is the notable two-speed model, while the DW734 and most budget units run a single feed rate.