It’s easy to think that design is design and that there isn’t a whole lot of difference between the types of design.
For the most part this is true. There are definitely fundamental principles that translate across genres. Principles like the golden ratio and the rule of thirds and all of that good stuff. (If you’re a designer, even if you don’t know the name you’d know the rule.)
Aaaaand then there are concepts that definitely don’t translate.
The great thing about web design is that you don’t need high resolution photographs. If you are buying stock images, this means you can buy the smaller (and usually cheaper) images.
As far as print goes, the higher the resolution, the better. You don’t deal with resolution as much in print design except for the dire need of a higher resolution image. Working in a higher resolution file means working in a larger file. Working on a larger file means higher processing needs.
CMYK and RGB are two different animals. I could tell you one is additive and one is subtractive, but that doesn’t mean a whole lot to most people. It makes more sense to me to realize that one is light based (the light from the computer screen) and one is pigment (or ink) based.
It is very difficult to match print and web colors since they work with two entirely different color systems. Metallic colors are difficult to achieve, but more difficult for print unless you have access to metallic inks.
In large blocks of text such as books, brochures and newsletters, it’s advised to use serif fonts for ease of reading. The serifs have a way of directing the eye and helping you keep your line placement. It’s especially beneficial for the dyslexic because of the more obvious differences in i, I, l and 1. (Yeah those are all different characters.)
On the web, it’s advised that you don’t have large blocks of text. Sometimes it’s unavoidable, but for a lot of sites the fewer words, the better. The more you break up your paragraphs, the better too. So the need for serifs is pretty much gone.
There are also some technical benefits to using sanserif fonts. For example, sans serif fonts can be sized smaller than serifs and still be readable. There are also some aliasing issues (hard pixilation) with windows and serif fonts.
On the web, it is best to have your navigation available on every page so that you can navigate anywhere from anywhere. The print equivalent would be to have the table of contents on every page. It certainly takes up space.
Good design transcends browsers and platforms and material, but unfortunately a lot of times it is defined by them. Since the very make up of Print and Web are different, by definition shouldn’t the design be different too?