I called my son, who used to work for a company that made a lot of this stuff - and then called his MIL who still works for that company .. here is the story they told me (it's kind of like a dog chasing it's tail):
Lard is rendered raw (uncured) pork fat.
Suet has different meanings, and may have different names ... depending on the context. But, suet is beef or lamb/mutton fat.
The raw fat from around the kidneys or loins are suet, sometimes called hard or flake suet. This is the preferred fat for pastries and puddings, like Ishbel mentioned. But, it is limited in quantity.
Raw fat from other areas (not rendered) is also called suet. However, when rendered it technically becomes "tallow". Tallow can undergo a couple of rendering processes ... to make soft or hard/flake tallow. The old oil blend that McDonald's used (when their fries tasted so good) was about 93% tallow - some other quick-food franchises with really good tasting fries used something similar. Hard flake tallow is also used in the pastry world - cheaper than hard-flake suet but has similar baking characteristics and flavor.
Fats, especially animal fats, carry a lot of flavor and offer qualities in baked and fried goods you will not get with Crisco or vegetable oils ... but also contain cholesterol, which vegetable fats don't.
I limit my instake of these goodies to once or twice a year.
"It ain't what you don't know that gets you in trouble. It's what you know for sure that just ain't so." - Mark Twain