The points in a Line Chart are spaced apart (typically by their x-axis value) and joined with straight line segments. A Line Chart is often used to visualize a trend in data over intervals of time – a time series – thus the line is often drawn chronologically.
Line Charts can also be used to compare changes over the same period of time for more than one group.
Follow the standard color order rules to determine color order for Line Charts. Each graph will have a different color with different line types and shapes, so you can easily differentiate each of them.
You can use either Pattern (line type or shape type) for Line Charts to help improve accessibility for your users. It's up to you to decide when best to use them.