"Semi-trailer is a general term, while transport semi-trailer is a function-specific type. The former includes the latter, with the core difference being 'scope size'.
• Semi-trailer: A general term for all trailers that must operate in combination with a tractor. Classified by purpose into transport, engineering, special-purpose types (e.g., dump semi-trailers, low-bed semi-trailers).
• Transport semi-trailer: Refers exclusively to semi-trailers with 'cargo transportation' as their core function, being the mainstream category of semi-trailers (e.g., skeleton-type, stake-type, van-type transport semi-trailers).
Simply put, a transport semi-trailer is a 'semi-trailer specially for hauling goods', while semi-trailers also include models for non-pure transport purposes such as hauling engineering equipment and special materials."
