Livewire has a great post contrasting the Obama and Romney campaigns. Here's a teaser with a few direct quotes:
Size: At the first rally, in Ohio, President Obama and the First Lady attracted 14,000 supporters. There were about 18,000 total seats. Then a little later, in Virginia, 8,000 packed VCU, which was a capacity crowd. Per Livewire, "both crowds dwarfed anything Romney’s been able to draw so far." In fact, "Romney crowds are still usually measured in the hundreds."
Passive vs Active: Per Livewire, "Everywhere you turned, supporters were being asked to hand the Obama campaign a phone number, address or social media account handle... This is not the scene at a Romney rally... Ann and Mitt Romney rarely if ever talk about voter registration."
Hint, quoting from Livewire: "Romney’s crowds, by contrast, tend to be whiter and older. ... [F]or now, the diversity is found at Obama’s rallies."
In other words, exactly what you might have anticipated. Dinky, demographically challenged assemblies vs. major, motivated, ultra-mixed crowds.
Now go over and read all of it here. Today was a good day for Team Obama.