Is there a difference in what media each will handle Randya?
I dont really know, Sign Warehouse will know about the 1204AS,
The thickness spec for the 1204 and the 16xx is a bit misleading, the spec is 0.3mm, but this is for calibration purposes, realistically it will handle the standard 1 mm media thickness in high head height.
The difference being that the machine is set up and calibrated using 0.3 mm thickness (uni and bi directional adjustments), so at 1 mm media thicknesses these calibrations are not going to be optimized. The thicker media are usually banner and will not show any noticeable differences in set up.