OK...now that we're really confused with so many types, let's take a look at what type of work each fork is made to do best.
Garden (English) Forks (aka One Serious Fork) This is the fork you want if your soil is undisturbed and/or clay or otherwise tough, hard soil. The garden fork has four long square, super strong tines that end with a diamond points for easy soil penetration. The best garden forks are forged from a single piece of carbon steel and have either a riveted socket or strapped handle connection. (the strapped handle connection is considered the strongest handle connection available.) Great for breaking up the toughest of soils, double digging and if needed, digging up root crops.
Digging and Spading Forks These forks are usually a little lighter in weight and have four triangular shaped tines with a flat facing the front of the fork for lifting. With their flat faced tines, these forks are good for digging in loamy, sandy or loose soil, aerating, mixing in nutrients, turning your soil in the spring and harvesting potatoes and other root vegetables.
Compost Fork The compost fork or pitchfork usually has four or more long slender, pointed tines that are turned up slightly for scooping or moving loose material without bending. Great for turning your compost pile or moving loose materials. Note: Manure forks look very similar and work very well as a compost fork thou the tines are not turned up as much.
Border and Shrubbery Forks These forks are just smaller versions of the workhorse garden fork. Despite their smaller size, these border and shrubbery forks are hard working garden tools. This fork is great for working in tight spaces like beds and between plantings and for the smaller gardener, a garden fork that is not so big and exhausting to use.
Potato Forks There can be a little confusion with what is a "potato fork" as different garden tool makers call completely different looking fork, a "potato fork." Some look just like a digging or spading fork with the flat faced tines for lifting the potatoes from the soil. In fact, some of the better garden tool maker's "potato forks" are made with the same strengths as their heavy-duty forks. The other type of potato fork you might encounter has many more (up to 10) slender tines that have blunt ends so as not to damage the root crops. This type of potato fork is generally for lifting of the root crops, not digging.
Broadfork Although very different looking than a traditional garden fork, the two-handled broadfork does a lot of the same chores, only on larger scale. With two hardwood handles fitted about shoulder width on a steel horizontal bar and 4 to 6 long tines; the broadfork is generally used for reworking ground that has already been broken up. This garden tool does a lot of work in a shorter time.
As with all garden tools; you can find most of these garden forks in all price ranges. The solid forged tools may cost more initially, but the quality, strength, warranty and the fact that you'll have a garden tool that you can pass down to the next generation far outweigh the cost. Plus, you're not tossing a bent garden tool into the landfill every couple of years.