All Purpose joint compound is the most basic and can be used for the vast majority of projects if you don’t want to use multiple different types of compound. This compound has a moderate amount of bonding agents so it can hold fairly well and also sands fairly well. You will need to have slightly more technique and time in order to get a great drywall job out of this.
Taping mud has more bonding agents, the compounds that hold drywall tape and panels better. This means that it is more difficult to sand and so, unless you want to use a lot of elbow grease, you shouldn’t use it for your final topping coat that you want smooth.
Topping compound has the fewest bonding agents. This results in an easy to sand top coat that you can get super smooth with, relatively, little effort. Without all the bonding agents, you wouldn’t want to use this as a taping compound because it won’t hold as well as a taping or all-purpose mud.
Most mud for homeowner use comes pre-mixed so that you don’t have to worry about the ratios to mix it. Mixing a little more water in, until it is the consistency of pancake batter, makes pre-mixed mud much easier to use and allows a smooth coat. This type of mud dries via evaporation so it needs longer to dry and tends to shrink some as it dries, requiring more coats.
Hot mud is bagged drywall compound powder that you mix with water in a specific ratio. This mud dries via a chemical reaction so the dry times are much shorter and much more predictable. There is also less shrinkage as it dries. A hot mud that says it will dry in 20 minutes will be dry in no longer than 20 minutes, whether it is on the wall or in the mixing bucket. Due to the much shorter working time, I recommend that homeowners should not use this mud for their first drywall project.
I mention lightweight mud because many people struggle to believe it can be used as effectively as the other drywall mud. I have discussed lightweight mud with several contractors that have used it. Half of them were suspicious it didn’t have as many bonding agents and that’s why it was lightweight. Others thought it was the greatest thing ever created. The jury is still out but in my house it is lightweight mud and nothing else.