girder和beam的区别？

girder n. 桁,梁 英文解释:a beam made usually of steel; a main support in a structure
beam:横梁
可见girder包括在beam之内,beam的范围更广

girder:A horizontal beam, as of steel or wood, used as a main support for a building or bridge.
大梁：一水平的铁制或木制的桁条，用来作为建筑物或桥梁的主要支撑物.

beam:A squared-off log or a large, oblong piece of timber, metal, or stone used especially as a horizontal support in construction.
梁、栋梁：建筑中用作水平支撑的，多为切成方形的圆木或长方形木材、金属或石头.