How would we know anything with out any information? Physical size? file size? what are your settings in the image size dialog box? What version of photoshop do you have? What OS do you have? How are you printing them?
Can you show us a screen grab of the difference?
All of these questions will help us help you.
Yeah. What Bruce said.
Is the printer cable OK? Fill a bowl with soapy water, and holding the two ends of the cable, dip the center part into the water. Now blow into the USB plug, and look for bubbles coming out of the cable. If you see any leaks, either repair with patches from the bike shop, or break an egg yolk into the water and boil. The egg yolk fills the leaks.
If you don't want to patch the cable. place an empty bowl under the cable while printing. This will catch the bits of print that fall out of the leaks so you can reattach to the print with Pritt stick or double sided tape.
Or get a big 9 volt battery with leads and small crocodile clips. Attach one clip to the printer, and the other to the print paper. You have just made an electrostatic device that will draw all of the print stuff through the leaky cable completely fooling the leaks.
If you can't find a battery, wear your most fluffy nylon jumper, and vigorously rub the printer up and down your chest for several minutes before printing.
If all that fails, reset Preferences and update your video card driver from the maker's website.
That will not work! It should at least be a 10 Volt battery!