01
Three inches covers most of what gets printed on the move
Shelf and bin labels, price tickets, pick labels, receipts and anything going onto a carton rather than a pallet. If the label you hand over today is a standard small one, this is the machine, and it is $100 less than the four inch.
02
Four inches is a full despatch label
The ZQ630 takes the 100 mm stock that a desktop or industrial machine prints — a full address label, a pallet label, a rack location. If anything you print has to come out at that width, the three inch cannot do it and no setting changes that.
03
The battery is the other difference, and it is a big one
This carries a 3250 mAh battery against the ZQ630's 6800 mAh. Roughly half. For a picker printing a few hundred small labels across a shift that is plenty; for a machine running most of the day on a trolley it is the reason to buy the bigger one even if three inches would have done.
04
No ribbon, which decides what the label can be asked to do
Every mobile printer here is direct thermal — heat onto heat-sensitive stock, nothing to load and nothing to replace. It also means the print fades with sunlight, heat and handling. Right for a pick label read this week or a receipt handed over now. Wrong for a bin label meant to survive a year on a rack in a hot shed, which is a thermal transfer job on a fixed machine.
05
And a warning for anyone who already runs ZQ600s
The Plus models are the same printer to look at and to use — Zebra redesigned the electronics so the line stays available — but they take different firmware and drivers to the ZQ600s they replace. That matters if you are adding one to a fleet somebody already manages, and it is the sort of thing found out on the day rather than in the quote unless somebody says it first.
Ask what the label has to survive before you ask which printer. A mobile printer earns its money by putting the label on the thing while the person is still standing at the thing — a count that is not written down twice, a carton that is not walked back to a bench. That is worth real money in a warehouse. What it will not do is print something that is still being scanned in two years, because there is no ribbon in it.
Both of these are 203 dpi, which is right for barcodes and plain text at this size. If you need small type or a dense 2D code on a little label, that is a 300 or 600 dpi conversation and a different machine.