How they really differ
These are different kinds of tools. CapCut assembles video. ElevenLabs produces audio. Many creators generate narration in ElevenLabs and drop the audio file into CapCut to cut it together with footage and captions.
If you compare only the voiceover feature, expect the dedicated voice platform to win on polish and the editor's built-in voices to win on convenience.
Using both
A common workflow: generate the narration in ElevenLabs, import the audio into CapCut, then add footage, captions and effects.
The verdict
For most creators this is not either-or. Use CapCut to edit, and add ElevenLabs when voice quality starts to matter.
Want the full write-up on each? Read our CapCut review and ElevenLabs review.