The main difference is, with an all-in-one printer, you will usually be able to scan, copy and fax as well as print. If you don't need any of this functionality, a standard printer will fulfil your needs. However, you can often get an all-in-one printer for the same price (or less) than just a printer these days, so it might be worth considering an all-in-one. You never know, it may well solve a long standing admin issue for no extra cost.