Duplex printing on Dell printers

I am looking for a printer that will print 2 sided pages. For years I have been printing one side, turning the page over, reinserting it into the paper tray, and printing the other side. I would like a printer that will do this automatically. I have been looking at the Dell B1260dn Mono Laser Printer and the Dell 2350d Mono Laser Printer. The Tech Specs for the B1260dn say "Duplex (Two-sided printing)  Automatic Duplexer" while the Specs for the 2350d say "Duplex (Two-sided printing)  Automatic duplex unit included as standard". Is this just a difference in wording or is there a difference between the two printers in how they do the duplex printing and in what the person has to do? Thanks for your help.