Although they have similar applications, spackle and joint compound are not the same. Their primary differences lie in their composition, consistency, and ideal use cases.

Spackle is composed of gypsum and binding agents, making it thicker than joint compound. It dries quickly and is easy to sand, which makes it ideal for small wall repair projects like filling nail holes or patching minor damage.

Joint compound, also known as drywall mud, consists of limestone and gypsum. It is primarily used for large-scale projects, such as taping and finishing the seams on newly installed drywall. It tends to shrink more than spackle and can be more difficult to spread.

While both products can be used to fill small depressions and cracks, spackle cannot replace joint compound for taping and mudding new drywall. Conversely, you can often use joint compound for small patching jobs typically done with spackle.

A nail in drywall cannot hold very much—usually only a few pounds. A nail in a stud can add support and hold around 20 pounds. If you are trying to hang something heavier, get some help from drywall anchors—toggle bolts are very strong and able to withstand more weight.

Yes, you can install drywall over plaster, but there are important factors to consider. While it can create a smooth, flat surface, it is often not the best approach. Installing drywall over plaster will increase the wall's thickness, which can cause issues with existing window and door frames that may no longer fit. You might also need to adjust power outlets to keep them accessible. A better, though more expensive, option is to remove the old plaster and lath entirely before installing new drywall. Drywalling directly over plaster seals in the old material, and if any problems arise later, you will need to remove both layers down to the structural beams for repairs. Given the potential complications, this job is best handled by professionals.

Drywall can be toxic to the environment and to humans in some cases. As drywall breaks down in a landfill and comes in contact with other organic chemicals, it can create hydrogen sulfide gas or leach into the groundwater. Additionally, the CDC recommends methods for controlling the inhalation of drywall dust when handled. While the common ingredients of drywall—gypsum, silica, and mica—are naturally occurring, they can cause irritation in some humans.