Breathtakingly shoddy analysis by the Verge
Consider this article: http://www.theverge.com/2013/7/19/4536042/jump-edge-next-early-upgrade-plans-compared
First, it's not a true apples-to-apples comparison, as the AT&T rate plan selected is for a $120 per month plan, while the equivalent plan on Verizon is $100 per month. So, from the outset you can expect there to be a difference of $480 over 24 months.
Second, the phones chosen are of different prices. The phone selected for AT&T is $640, and the phone selected for Verizon is $650 for a difference of $10. This is no biggie, since there isn't much difference, but this amount will come in to play later.
The real error is in the "Combined fees, months 13-24". For AT&T, the amount presented is $1823.88. If you take away the ~$120 per month rate plan fee for the final 12 months, it comes out $384 for the hardware payments ($1823.88 - $119.99 * 12 = $384). That amount is EXACTLY the same as the figure for months 1 to 12. This cannot be correct, as the payments for Next is prorated over 20 months, not 24 like it is for Edge. So the REAL amount should be $256 ($32 * 8).
With this $256, let's calculate the correct amount for months 13 to 24:
$256 + $119.99 * 12 = $1695.88
So now let's get the combined total:
$1439.88 (plan fees 1 to 12) + $384 (hardware pmt 1 to 12) + $1695.88 = $3519.76
Now let's compare with the total for Verizon:
$3519.76 (AT&T) - $3049.98 (Verizon) = $469.78
If you take into account the difference in phone prices of $10, you get a real difference of $479.78.
Congratulations. You just showed, in the most convoluted way possible, that a rate plan of $20 more per month will cost you $480 over 24 months.