Mild tasting canola oil is produced from rapeseed, a member of the mustard family, along with broccoli and cabbage. Lard, made from pork fat, varies from strong tasting types to those processed with milder flavors, such as leaf lard taken from the fat around the pig's kidney. You can use either lard or canola oil in baking, but there are trade-offs with each fat, and certain foods that do well with one or the other type of fat.
Because lard contains more saturated fat molecules than canola oil, the molecules retain their solid state when they are rolled into a pastry dough. The fat remains solid, coating each particle of flour instead of merging with the flour and causing a sticky gluten to form, as is the case with oil. The solid fat and flour create layers within the dough. When the layers hit the heat of the oven, the fat melts, steam is trapped in the empty space, and flaky pastry results.
Whether you use canola oil or lard for a cake depends on what kind of cake you want. Solid fats, such as lard or butter, are better at holding the air bubbles in the cake batter, leading to more airy cakes. Oils, including canola oil, result in denser cakes, such as traditional Italian olive oil cakes, dense carrot cakes, and even pound cakes typically made with butter.
Although unusual, some cookies rely on either lard or oil instead of butter. In countries where people use lard for traditional recipes, you'll also find lard in cookies. In Mexico for example, Day of the Dead raisin and nut cookies rely on lard. Cookies made with oil are typically more cake-like than other cookies -- their texture is more airy and light rather than dense and chewy even though they still have the shape and size of cookies.
If you want to lighten up the amount of saturated fat in your diet, you'll choose canola oil over lard despite its baking drawbacks. Canola oil and lard are as far apart as they can be in the amount of the saturated fat they contain, with canola oil having the least amount of all common oils at 6 percent, lard having 39 percent. Canola oil also has more healthy monounsaturated fat, with 62 percent compared to lard's 45 percent.