It's one of the most important decisions every student interested in training as a lawyer at a large commercial law firm must make.
Telling the difference is harder than you think
Once upon a time, it was easy to spot the difference between English and US firms.
On the one hand, there were blue-blood City stalwarts that might have developed a network of offices across the Middle East and Asia, but at heart were still straight-laced English law firms.
On the other, there were the New York and Chicago players – some had had offices in London for years and claimed to have gone native, but when push came to shove their City operations were always going to be a satellite to the stateside mothership.
Now, however, the position is less clear.
Most international English and US firms are keen to publicise their large overseas networks of offices, from which they generate an increasingly large proportion of their revenue.
So the idea of them having a single nationality has become somewhat meaningless, and even passé – for example, some of these firms even claim not to have a head office.
The distinction between English and US firms has also been muddied by an increasing number of transatlantic mergers.
Tie-ups such as that between Lovells and Hogan & Hartson in 2010, or the 2013 merger of Norton Rose with Fulbright & Jaworski mean that an increasing number of the key graduate recruiters in the commercial law firm sphere are neither truly English nor US firms.
Both of these deals resulted in an equal partnership between a strong City brand and a US powerhouse, and added to what is arguably a growing new category of law firm in the City.
There are pros and cons both ways
However, enough clearly English and clearly US firms remain in the City to make drawing distinctions between them meaningful.
One of the first differences often flagged up between English and US firms is salary levels – you're likely to pocket more from an American outfit.
Why is this the case? New associates in New York have historically been paid more than their peers in the City because of their much higher law school debts.
And when US firms began to offer training contracts in their City offices, many chose to offer London recruits a well above average market rate, both for the sake of equality between their trainees on both sides of the Atlantic and also to entice graduates away from more established English City firms.
Today, even US firms with well-established London offices often still pay more than English firms, with the differences becoming more significant on qualification.
A higher salary at a US firm, however, may come at the cost of a higher hours expectation – the amount of time your firm will require you to work for clients every year once you're qualified, which you'll often find formally stated in your contract.
In addition, having a magic circle or other top long-established English firm on your CV still counts for a lot as you progress in a legal career in the City, and some graduates take the view that an extra few thousand pounds a year doesn't compensate for losing this kitemark.
However, if you have your sights set on working on Wall Street or in certain other parts of the globe, a stamp of approval from a US "white-shoe", the name given to Wall Street's top firms, is likely to help you more.
Also on the plus side for US firms, you'll usually be part of a smaller intake because their offices in London are often smaller than those of English ones.
Swimming in a smaller pool can mean more responsibility and a better chance to network with colleagues across the office, but it can also mean less formal training and fewer support services.
Ice and a slice?
What do things look like on the ground? An associate I spoke to at a recently merged English/US firm hadn't noticed many changes coming about from the join-up she'd experienced. "I think [the firm] is still quite British," she said.
Apart from more in-depth and formal US-style self-evaluations and performance reviews, the only significant alteration she'd noticed was "the ending of the weekly drinks trolley in the office on Thursdays – [Americans] don't understand drinks in the workplace."
Some cultural divides, it seems, are too great to ever be bridged.