The European Union is facing a higher 15% tariff rate on its goods imported to the U.S. compared to the 10% levy the U.K. has agreed to. "In theory, the UK benefits," Philip Shaw, chief economist at Investec, told CNBC.

The European Union and the US appear to differ on some fundamental details in their new trade agreement, underscoring the difficulty they’ll have in turning this deal into a reality.

Von der Leyen said Trump was a “tough negotiator,” adding that any trade deal with the EU would be the largest struck by the US president.