The two dishes are quite similar, and are also similar to Cottage Pie. All have a beef or lamb layer topped with mashed potatoes. Many experts say that technically a Shepherd's Pie uses lamb, while a Cottage Pie uses beef, so in that regard, the French Hachis Parmentier is closer to Cottage Pie. Also, both Shepherd's Pie and Cottage Pie often contain more vegetables mixed in with the meat than in Hachis Parmentier. Finally, an egg yolk and lots of grated cheese is generally mixed with the mashed potatoes in Hachis Parmentier, which is not typical of Shepherd's Pie or Cottage Pie.