1. The first big difference is how long it takes to find out who you'll actually be swearing in. In the US, this process takes exactly 84 years.
And in the UK, well, there were about 90 minutes between Theresa May lauching her campaign to be the next prime minister, and being announced as the next prime minister by a man called Graham.
2. In the US, huge crowds witness the big moment that the president is sworn in on the National Mall in Washington, DC.
In the UK, you officially become prime minister in a private meeting with the Queen.
3. The exact moment of becoming president happens at noon on 20 January, which is about the time of the recitation of the oath of office.
And in the UK, the magic moment happens when the Queen ~invites you to form a new government~.
4. After the deed is done, the new US president gives a stirring inaugural address; some of these are long-remembered and very famous.
Who knows what such immortal lines await us on Friday?
Anyway, the new prime minister also gives a speech, but to a much smaller group of mostly bored journalists in front of 10 Downing Street.
Nobody really remembers what is said in them.
5. But what happens to the outgoing president on Inauguration Day?
Then they get in a helicopter, Marine One.
And they helicopter the fuck outta there.
And the new president waves at them like byeeee.
In the UK, the outgoing prime minister gives a sad speech to the same pack of mostly bored journalists.
Then he kind of walks off...
...and gets into a sensible midsize family car to go and see the Queen.
The "outgoing prime minister in a sensible car" look is definitely more grim than the "fucking off in a helicopter to spend my retirement painting dogs" look.
6. But it's not over yet for the Americans! Next there's a massive parade with lots of military types and large brass instruments.
Everybody marches by a special presidential box and it's all very grand.
And the new president goes out there and gives the people what they want.
In the UK, after she's done meeting the Queen, the new prime minister leaves Buckingham Palace and gets into a sensible midsize car...
...and drives along to get back to Downing Street...
...and then there's a bit of a walk at the end, and she does her speech to the bored reporters.
Best-case scenario, people like you and wave flags at you.
7. After the parade in the US, there are still loads of inaugural balls to attend. Like this one in 2009 with Beyoncé.
The balls are glamorous and ritzy affairs – here's the Obamas having a dance on a giant presidential seal.
In the UK, the new prime minister doesn't get 10 balls, or even one ball. But there IS this moment after arriving at Downing Street where some employees clap at you, so that's nice.
And there may not be a big grand dance with the husband or wife, but there is a nice wave from the steps of Number 10.
Or even an awkward snog. And who would want a parade when you can watch your new leader awkwardly handle their partner?
It's the finest British political tradition of all.