That's another difference. With Zapmarks, there is no "most of the time". If you type a keyword you have set up, and hit enter, you will get exactly to where you wanted to be 100% of the time. Once you've got the keywords baked into your brain, accessing them from everywhere is very handy!
In either case, most of the time when I type "n" I get HN or "m" for mail and so forth. I can't really see a good use case for this.