He's got good genetics for building muscles but their actual muscle shapes are not the same. Sergio's abs/obliques were much better (Sergio Jr's obliques already stick out). Jr's biceps are more peaked. Sr's calves had lower insertion points. Sergio's chest had wider shape. Sr had longer muscles/lower insertions just about everywhere (triceps, biceps, calves) but it looks like Jr's got slightly better lat insertions. Both had good quad sweep but sr's are shaped with a more rounded nature, jr's are more square/blocky.
Both have great genetics but they're not that similar.