First, their properties differ.
1. High-frequency welded steel pipes: These are produced by heating and melting the edges of hot-rolled coils using the skin effect and proximity effect of high-frequency current, followed by pressure welding under the action of extrusion rollers.
2. Straight seam welded steel pipes: These include double-sided submerged arc welded straight seam welded steel pipes and high-frequency resistance welded steel pipes. High-frequency resistance welded steel pipes are abbreviated as ERW. Submerged arc welded straight seam steel pipes are further classified into UOE, RBE, JCOE, etc., according to their different forming methods.

Second, their materials differ.
1. High-frequency welded steel pipes: High-frequency resistance welded steel pipes have a different welding process than ordinary welded pipes. The weld seam is formed by melting the base material of the steel strip, resulting in better mechanical strength than ordinary welded pipes.
2. Straight seam welded steel pipes: The main materials for straight seam welded steel pipes include Q195, Q215, Q345, and X42 pipeline steel series. Straight seam welded steel pipes are available in two types according to the specified wall thickness: ordinary steel pipes and thickened steel pipes. They are also classified by end type: threaded and unthreaded.

Thirdly, their characteristics differ:
1. High-frequency welded steel pipes: These have a smooth surface, high precision, low cost, and small weld reinforcement, which is beneficial for 3PE anti-corrosion coating. The welding method of high-frequency welded steel pipes differs significantly from that of submerged arc welded pipes. Because welding is completed instantaneously at high speed, ensuring weld quality is much more difficult than with submerged arc welding.
2. Straight seam welded steel pipes: The length of straight seam welded steel pipes is mainly divided into fixed lengths and variable lengths, depending on customer requirements. The length is generally 6-14 meters. Large-diameter straight seam welded steel pipes may require two steel plates to be rolled, resulting in a double weld seam.