1. The 2008 race changed how Democrats perceived her
In her first run for president, Clinton struggled to get out of the large shadow cast by her husband a.k.a the 42nd President of the United States. Clinton's willingness to except her loss to President Barack Obama in 2008 with aplomb coupled with her service as America's top diplomat imbued Clinton with a gravitas and respect that wasn't as present in her 2008 campaign. Because of that, she started at a higher elevation - and with a deeper reservoir of goodwill among Democratic primary voters - than she ever had eight years ago.
2. No drama
In 2008, the Clinton campaign felt like the most dysfunctional of families. She jettisoned her original campaign manager as well as much of her inner circle halfway through the race. Once it became clear she wasn't going to win - and it became clear long before she ended her campaign on June 7, 2008 - her aides fought viciously behind the scenes to blame each other for what went wrong. Bill Clinton was a permanent distraction, regularly veering far off message in his attacks on then-candidate Obama. All of that stood in stark contrast with Obama's campaign, which prided itself on its lack of drama.
Clinton learned her lesson from that race. She brought in a (mostly) new team for the 2016 race led by low-profile operative Robby Mook, a nerdy, self-effacing numbers geek who promised a campaign built on organisation and efficiency. Clinton stuck with Mook even after she lost New Hampshire by 20-plus points to Sanders, and there was considerable chatter that a change was needed.
"There was less a projection of entitlement, less campaign drama, less petulance during hard times, less unfortunate focus on the former president," said Jim Jordan, a veteran Democratic operative of Clinton's 2016 effort.
3. Bernie Sanders not Barack Obama
Clinton won this nomination before any votes were cast. She cast herself as such a prohibitive favourite that she scared away the likes of Joe Biden or any other top-tier candidate who could have been a real problem. What was left was Sanders, a 74-year-old democratic socialist from Vermont. While Sanders drastically overperformed - a sign of Clinton's inherent weaknesses - he was never able to recreate the three legs of the Obama electoral stool: Affluent, highly educated whites, young people and minority voters. Sanders got the first two but was beaten incredibly badly by Clinton among black and Latinos - making his path to the nomination impossible.
To Clinton's credit, she saw that without minority votes, Sanders's maths wouldn't add up. And she and her team executed brilliantly to ensure that she monopolised that vote. "The coalition she smartly built early focused on African Americans and Hispanics," said Patti Solis Doyle, who was Clinton's first campaign manager in 2008.
4. Donald Trump
As the primary process wore on, it became clearer and clearer that Trump would - against most odds - be the Republican nominee. That development helped Clinton drive a contrast with Trump that worked in her favour in the primary. Clinton seized on that comparison in the race's dying days; her speech slamming Trump on foreign policy was evidence of a belief that talking more about her experience in contrast to his was a winner in the primary.
"I think having Donald Trump as the main foil was helpful because it helped accentuate (with Democrats) the strength of her candidacy - the 'ready to be President on Day One' credential," said Democratic pollster Fred Yang. "I think especially in the last week or so, as she got closer to the nomination, she stepped up her explicit contrast with Trump, and I think that helped."
5. The calendar
In 2008, Clinton lost the race not in January but in February when a series of heavily Republican states held caucuses where Obama swamped her. It was in February where Obama built the delegate lead he would never relinquish.
There was no such run of states this time around. While the earliest part of the calendar favoured Sanders with a caucus in Iowa (one consistent thing from 2008 to 2016: Clinton never performed well in caucuses) and a primary in New Hampshire, much of February, March and even April worked to Clinton's advantage with a slew of southern states with large black populations dotting the electoral landscape. Sanders, on the other hand, had to hold out until, well, now, when a series of states, such as South Dakota and Montana - as well as California - voted.
As a sidebar to the calendar conversation: Mook and the rest of Clinton's inner circle understood the delegate allocation process far better this time around than did the 2008 team. Clinton won the nomination in 2016 in the same way she lost it in 2008 - through the grinding accumulation of delegates to the point at which the math became determinative.
"In 2008 they didn't understand the delegate fight anywhere near the way that the Obama team did," said one senior Democratic consultant granted anonymity to speak candidly. "This time Robbie and team knew exactly what they needed to do to get the delegates they needed."
