What's the difference between a cross-line, 360-degree, and rotary laser level?

Cross-line lasers project a single vertical and horizontal line and are ideal for tiling, picture hanging, and cabinet work. 3x360 (or 4D) units throw full planes around the room for layout and electrical work. Rotary lasers spin a beam and pair with a detector for long-range outdoor grading and excavation, which is why reviewers reserve them for large jobsites.