A:
That is one of the primary differences between the models. However, the 6520 is intended for small business, as the 5535 is more consumer friendly and intended for home use. The 5535 can also print almost twice the amount of ppm. the 6520 Besides a few minor refined features between the two. the 6520 has a bigger LCD touch screen as well. In terms of faxing however As Faxing is becoming slightly phased out, so will the ability with some of these printers. If you do like to Fax, I recommend having a printer that retains this ability to fax.
I know Bestbuy does have some comparison tools as well to compare models. However, there are other sites like cnet that are more specific to comparing and reviewing.