I would like some help with my english. I wish to write in correct english the following:

Say I am building a machine that delivers something, and it delivers it in sealed packages. Sometimes the packages have something printed on it. And sometimes it does not. 

How can I name these packages? or the process? 
For the one without printing I would say "printless package" but I don't know for the other case. And I am even thinking that that does not sound correct.