Lines and Detail Lines?

[Bluefairy]

What is the difference between detail lines and lines tool?

[Craig_L]

A detail line is a 2D line, only visible in the current view you have drawn it in.
The line tool, if you mean the linework tool, will overwrite a currently drawn 2D line, or representative line of a 3D element with whatever you select. So that tool can not, itself, draw a line, it can only change the properties of an existing line