When you write for print you can make all kinds of claims, you can even stretch the truth. You shouldn't, but you can. Write like that online and you'll be found out and punished in a heartbeat. The web is a shared space. All your readers, customers, and prospects are connected.
If they have an experience they don't like, they will share their displeasure through forums, lists and shopping comparison sites.
*This approach to writing online is essential when writing for the internet.