Many people use record drawings and as-built drawings to mean the same thing. Some specs separate them, so read the definitions in Division 01.
Each trade marks its changes on a set kept on site. A plumber marks the real route of underground pipe. An electrician marks relocated panels.
Record drawings are a closeout requirement. Final payment can wait on them. Some specs ask for digital files in a set format.
Carry time for this in your bid. Mark changes as they happen. It costs far more to rebuild them from memory at the end.