Internal Link Juicer is pretty similar to Link Whisper but lacks a lot of functionalities. It is an automatic internal link builder plugin that you can configure for specific keywords, which is then used to automatically link to the specific posts you have configured in the plugin. Since internal link building is effective only if it is relevant and for that to happen, you need control of every aspect of the process all without having to put in a lot of effort, Link Whisper does a better job than Internal Link Juicer.