Lag screws are also known as lag bolts and are typically a larger type of screw used to secure heavy wood beams or to fasten wood to masonry or concrete. Their use varies based on the type of head and thread but are generally bigger and longer than wood screws. There are also a few other differences between lag screws and wood screws.
A lag screw or a lag bolt has a thread used in a conjunction with a nut. The nut is fastened and it pulls the bolt through to hold things together. The thread on a wood screw is different as it is self-threading. This means the thread on the wood screw is used to also drill the hole for it.
A lag screw is meant for heavy-duty loads. It is a safe and secure way for holding support beams or large beams because the nut provides a counter to the hold. A wood screw provides less load bearing because it only uses its own thread to hold things together.
In order to use a lag screw you will need to make a hole using a drill. This is because of its thread type. A wood screw doesn’t require any drilling as it will use its own thread to make the hole. This makes them better options than lag screws on smaller jobs that don’t require an extra strong hold.