As we talk about the printer, we use print resolution to compare the print quality. DPI means “Dots Per Inch”. It refers to number of dots the printer can print per inch. It is used to define the print resolution, which will affect the print quality. The higher the DPI, the finer the print.
If laser printer prints with 300 dpi, it will give you a good print for normal text. Nowadays, most laser printers in the market offer the standard print mode at least 600 dpi, some color laser printer is able to print up to 3600 dpi.
Less DPI means less dots will be printed on page, will it save toner? Yes, but not too much. The dot is printed with 300dpi is bigger than it with 600dpi, take size into account, the saving of toner will not be significant, especially for text printing.