gThumb is an image viewer and organizer with a couple of limited options to also edit images. Developed by The GNOME Project
License: Open Source
ACDSee is a powerful photo management and editing software with extensive features like RAW support and batch processing, making it ideal for professional photographers. gThumb, on the other hand, is a lightweight and fast image viewer and organizer primarily suited for casual users and those on Linux, lacking some advanced editing tools and RAW file compatibility.