Is there a difference between plastic sided and cardboard sided bobbins?
Either type is fine. Plastic bobbins are reusable; cardboard bobbins are disposable. Because the plastic-sided bobbins are so smooth, they may continue to spin even after your machine stops and cause backlash. Some machines seem to work better with the cardboard-sided bobbins because the cardboard sides provide more friction and backlash is usually not a problem. If it is, the bobbin tension may need to be tightened.