Both the Pen Tool method and the Image Trace method can be used on any image; however, some images will make one method easier than the other. Remove Background using Image Trace Method in Illustrator ...

Placing a raster image into Illustrator CS2, CS3, or CS4 ( ) via File -> Place and access the Live Trace Options from Object -> Live Trace -> Tracing Options, or use the button on the Control panel.