Why sunlight produces more spectral lines than other light sources

Answer 1

I don't think it does. And are you talking emission lines or absorption lines? I strongly suspect (although I've not counted them) that uranium produces more spectral emission lines than you can get from the sun.

Answer 2

Spectral lines

Answer 3

FYI. There are spectral emission lines and spectral absorption lines.
If you can describe what you're studying I may be able to guess where you're going with this.
Otherwise, here is link that may get you started.
http://phet.colorado.edu/en/simulation/blackbody-spectrum