这两者之间没有实际区别.如果未配置，则两者都将在本地模式下执行代码.如果配置了master(通过--master命令行参数或spark.master配置)，则将使用相应的群集执行程序.

There is no practical difference between these two. If not configured otherwise both will execute code in a local mode. If master is configured (either by --master command line parameter or spark.master configuration) corresponding cluster will be used to execute the program.