I haven’t used Exposure hands-on so the following comments are based on the Exposure website documentation (there is an extensive set of tutorials and videos) and reviews I found on the web. Exposure X6 is very similar to Lightroom in its user interface. It provides file management/Digital Asset Management tools including metadata editing, virtual copies and virtual collections. It has a comprehensive RAW editing workflow with non-destructive editing pathways (similar to LR). Unlike LR it supports layered images with blend modes, masks, opacity etc. so you can make composite images, or apply filters to layer copies for more flexible editing. The user interface is customisable so you can move or hide different editing panels to suit your personal workflow. You can also use Exposure X6 as a plugin to Lightroom and Photoshop.
Note that Exposure X7 is “Coming soon” at the time I write this (august 2021), which they tout to contain new masking tools, new workspaces and improved image quality.