Watts describe input power
Watts tell you how much electrical power a product uses. For an energy comparison, use the actual system input power at the intended setting. A lower wattage is useful only if the proposed installation still serves the lighting task.
Lumens describe light output
Lumens quantify the amount of visible light emitted. They do not tell you where that light will land after the fixture is installed. Two products with similar output can produce different results because their optical distributions are different.
Distribution describes direction
The fixture optics direct light into a pattern. A pattern suited to an open area may perform differently in a narrow aisle or along a property edge. Photometric data helps compare those patterns at the planned height and position.
Illuminance describes light reaching a surface
Lux and foot-candles describe light arriving at a surface. They belong to the installed layout, not simply to the wattage printed on a fixture. The surface location, mounting geometry, and obstructions all matter.
Compare the whole installation
Bring together input power, output, optical data, and the layout. Then examine visual comfort and the way the space will be used. A photometric review can make the difference between comparing catalog numbers and comparing project outcomes.