Well, technically, all pecans are hickories, but not all hickories are pecans by any means. All species of hickory are in the genus Carya. Pecans are Carya illinoinensis.

Culinarily, by convention, oblong/cylindrical nuts with dark shells are called Pecans, those more flattened with lighter shells are called hickories. Pecans are much easier to shell than hickories such as shagbark and shellbark, but the nuts of both are very tasty. I'm sure that pecans are what you want.

Grafted specimens will come into production in about half the time(or less) that you'll be waiting for seedlings to grow through their juvenile period and reach bearing age.
For pecans, that will translate to 5-10 years or so before they start bearing a few nuts, as opposed to 12-20 years for a seedling pecan to begin bearing.
Hickories - even slower. I've got grafted hickories that have been in place for nearly 15 years, and still no blooms or nuts.
By and large, pecans will be more productive than hickories - but the hickory flavor is superior to that of pecan.
Heck; plant some of both, if you've got space for them.

Here is a link that might be useful: Nolin River Nut Tree Nursery

It's hard to describe the taste difference, but to me the pecans have a low rich flavor, the hickories have a higher intense flavor. Pecans are muich easier to shell than hickories. I used to gather hickory nuts for my gramma in Upstate NY. They were so much work that she used them only in frosting for a plain yelow cake. It was superb! The ground nut frosting was incredibly flavorful.

Songbird:

I kind of wondered about the taste difference. I thought there might be one and now I may plant a hickory or two in addition to the pecans.

Speaking of taste, do you have this recipe you mention or can you possibly re-create it from memory? I'm sure I'm not the only one who would like to try it.

Rolf