I think so too.
Like Dave says, it's how tall the overall sight is. I'm not sure what the line # means, unless they have grooves made into them to reduce the sun reflection. Usually the higher the number the finer the lines (like pitch of a thread)
Here's the perfect time to upgrade your sights. Go tritium night sights and you will never look back!
http://www.smith-wesson.com/webapp/wcs/ ... y_rn=16262
Any shop can put the sights on, or we can help you, if you want to try yourself. S&W presses them in so you need a vise to hold the slide or the special sight remover tool. Normally they come out left to right with a bit of force applied.
S&W doesn't use locktite, but I do when I set them. (Locktite can be removed easily with a bit of localized heat).