I shouldn’t devote too much time to this thread today (I *do* have this thing called a job), but you should recognize that where Secretaries within your system serve at the pleasure of the President but are not themselves elected officials, Cabinet Ministers within the Westminister system are generally elected members. I guess the nearest equivalent would be if 97% of your secretaries of Labour, Housing, Defense, Environment, etc., were Congressional representatives. Ministers can be appointed from outside, but it tends not to happen very often.
Not that political appointees are not beholding to those who put them there, or on the same page, ideologically, but they might not be quite as driven to act in a manner that gets them and their party re-elected. That’s speculation on my part, though, not necessarily reality.
Perhaps one manner in which differences between our respective systems might emerge is that cabinet, being made mostly up of elected MPs, does not automatically assure that whomever is the minister of X is a SME in that area, since cabinet, and your talent pool, is comprised of whoever managed to get elected. Within your system, it is quite conceivable that any given bureaucrat may have a difference of opinion with the Secretary of their agency, but the working assumption is that whomever was appointed as Secretary has some expertise in that area. Within the Westminister system, unless you get lucky, its potluck. You may get a minister who is up to speed (particularly if it is a re-elected government and they retain the same portfolio), you may get one who is familiar with cognate areas and a fast learner, and you may get someone who requires training. Note as well, that it is common practice, and component of succession planning, to move some individuals from portfolio to portfolio, such that they become well-rounded and groomed for a potential role as PM. Under your system, there is no underlying assumption that the Secretary of Labour will be shifted over to Secretary of Defense, to make them more electable 3 years hence.
All this aside, one assumes they are all eager learners. The handicap they all come with, unless former bureaucrats themselves, is that they tend to be largely unfamiliar with how the bureaucracy works.