An apparatus and method for encoding video data and an apparatus and method for decoding video data are provided. The encoding method includes: splitting a current picture into at least one maximum coding unit; determining a coded depth to output an encoding result by encoding at least one split region of the at least one maximum coding unit according to operating mode of coding tool, respectively, based on a relationship among a depth of at least one coding unit of the at least one maximum coding unit, a coding tool, and an operating mode, wherein the at least one split region is generated by hierarchically splitting the at least one maximum coding unit according to depths; and outputting a bitstream including encoded video data of the coded depth, information regarding a coded depth of at least one maximum coding unit, information regarding an encoding mode, and information regarding the relationship.