A screw usually forms or uses threads in the material being fastened, while a bolt normally works with a nut or a tapped hole to clamp parts together. That distinction matters because screws are often selected around drive type, thread form and pull-out resistance, while bolts are selected around shank length, thread length, nut fit, washer use and clamping load.
Nuts are not an afterthought. A bolt and nut must match in thread size, pitch and strength category, and the washer or locking method should suit vibration, surface hardness and access for tightening. If the joint may move, heat, corrode or be serviced repeatedly, the nut-and-bolt combination often deserves more attention than the bolt alone.
Start with the joint, not the catalog name. A furniture board screw, a self-drilling roofing screw, an anchor bolt and a pipe U bolt solve different problems. Describe the base material, the part being fixed, the hole condition, access for tools and whether the fastener is permanent or removable. This prevents a common mistake: ordering a familiar fastener type that does not suit the actual joint.
Match thread and head style to installation. Coarse threads often suit softer materials, while machine threads require a matching nut or tapped hole. Hex heads are practical for higher tightening force and site work; countersunk heads sit flush; cross or other recessed drives may suit light assembly but can strip if the tool fit is poor. For self-tapping or self-drilling screws, confirm the material thickness and pilot-hole or drilling requirement before ordering.
Choose the finish around exposure and assembly risk. Zinc plating, hot-dip galvanizing, Dacromet-style coatings and other finishes are selected for different corrosion conditions, appearance needs and thread-fit effects. A heavier coating can change how nuts run on bolts, so confirm compatibility instead of treating the finish as a simple color choice.
Give the supplier the details that change the answer. Send drawings or photos if available, plus diameter, length, thread pitch or standard, head type, drive type, material grade if specified, finish, quantity and packaging preference. If you are comparing alternatives, ask Hebei Wotu Fastener Manufacturing Co., Ltd. to confirm which fastener type is suitable for the application rather than only quoting the nearest size.
