With Mirror - for Roku TV you can get a smoother screencasting experience on Roku devices.

Screen Mirroring

• Use this option to put the screen of your Mac on TV. In the source, you can select which screen (or attached monitor) you want to display on TV. The latest version of the screen mirroring function already supports simultaneous audio transfer to the TV, please follow the UI instructions to enable the sound option.

Media Steaming

• Use this option If you want to play video or music files stored on your Mac on a big screen TV. Add media file in the playlist and push it to play on Roku device.