No, the UI and rendering wngine are different. Brave is just a clone/derivative of the Chrome source code withminor feature additions. FF previewis not based

No, the UI and rendering wngine are different. Brave is just a clone/derivative of the Chrome source code withminor feature additions. FF previewis not based on Chromium, has its own unique UI and has more features and ability to install a small amount of addons (for now).