This can be misleading as the published data does not include the inherent losses in the optics (lens) used to focus the light. It's also dependent on the hid being driven to the same conditions, which again is not always the case, and effective brightness can vary enormously if the same output is distributed differently.

Most, if not all, decent lights available use hid of some form or another. In the good old days of yellow tinted halogens, light power output was published in Watts. Because an hid is a much more efficient method of producing light than halogens, of hid lights for that matter, the use of Watts to compare the outputs is now redundant. Instead hid manufacturers publish their data in lumens. so that? It's not that important that you understand, actually. It's much more important that you understand the limitations.
In theory more lumens means a brighter light, but in practice it's not that simple, things never are hid manufacturers simply republish the data they get from their hid supplier for lumen output.