J1 is equipped with Independent dual extruder structure, which acts like two printers printing two objects simultaneously. With two separate extruders moving independently of one another through the X-axis, it runs two prints at the same time.
On the other hand, Artisan or 2.0‘s dual extrusion module is another structure which conjoins two separate extruders in one module and shares one X-axis, It can only print with two heads together, and is not allowed to print two models at the same time.
However, they also have similarities. Once you experience dual-material printing, both of them can satisfy your needs. You can mix two different materials or colors in one single print.