Yes, there can be a difference, there are different types of glass used when grinding the lenses and different types of coatings used which can make a difference in the quality of performance but a Plossl is a Plossl as far as design goes. You usually get what you pay for, unless cost doesn't matter to you I suggest going the middle of the road on cost. If cost doesn't matter I suggest Tele Vue. : I recently purchased a Meade etx-90/ec which comes with the super plossl 4000 26mm eyepiece. I want to buy additional eyepieces for higher magnification but I am confused about the different types. I have seen other brands as well as plossl eyepieces for much less than the super plossl eyepieces. Are these as good as the SP 4000 series? This scope is supposed to have superior optics and it seems foolish to save a few bucks and reduce the clarity of what I want to see but if they are the same or somewhat comparable I don't want to pay more for the same thing. Also which sizes are best to buy for this scope? Thank you in advance for any help.