We sell them both. The avic n-1 has yellow page phone # search...if you only know #, it will guide you. It also is a single din flip version, not as stock looking as the 2454. Both are touch-screen, both have front/rear/sub pre-outs. Both are 6.5" screens. Both have voice guidance. The 2454 has 2 disc inserts, 1 for cd, 1 for nav or dvd. The n-1 has xm capabilities.
If you have a double-din dash(my wife has the new Expedition) then the 2454 looks factory as we have in her Expe.
That's a few comparisions...BTW I'm stuck in Las Vegas @ CES and both are being replaced this year.
I'm going to post a profile on the new when I get back to Daytona.
Hope this helps and if any more questions, I'll do my best to answer.