This may help, but idk
The president of America is frequently referred to as the world’s most powerful person. However, the federalstructure of America has put restraints on the power of the president that do not occur in Great Britain, lead by a Prime Minister. The powers of Congress and the Supreme Court are used as a balance to the power a president might accrue in his time in office. The Constitution of America ties the president down as to what he can and cannot do. This codified document can only be changed by the Supreme Court. Such a constraint does not exist in Britain though the input of the European Court on formulating some British legislation is difficult to assess but does not come into the same league as the power that that the Supreme Court of America has.