The male skeletal structure is completely different to the female skeletal structure, and those differences can only be somewhat corrected for by surgery. The differences manifest in facial expression, gesture, movement, and silhouette.
Since humans evolved to spot predators visually more so than through any other sense, we take in details as a whole, and even if we can’t say why, like cats, we notice when our eyes spot something “off.”
Male faces have a brow ridge females don’t have, and the jaw is shaped differently. Male features have a different proportional separation as well. These differences manifest in facial expression.
Male shoulder joints are angled differently than female shoulder joints, and this affects gestures with the arms.
Male torsos are proportionately shorter than female torsos, while male arms are proportionately longer than female arms, and those differences manifest in entirely different silhouettes, an effect that will made larger if the surgically implanted breasts atop the male skeleton are large.
Male hands and feet are much larger than female hands and feet, and those differences will be readily apparent in any action involving fingers and hands and, for feet, while walking.
The male gait is different from the female gait because the pelvis is angled differently.
The shoulder-to-hip ratio is completely different, and this is noticeable in silhouette.
Unless expensive vocal cord surgery has been performed, a male speaks in a completely different register to a female voice.
It takes both extraordinary surgical effort and extraordinarily good luck in having been born at the end of the bell curve in which these skeletal differences are minimised, to counter these differences.