Leaves look like Stewartia however I don't see any sign of the very characteristic zig-zagging of the branch stems that S. pseudocamellia typically produces. But that may just be distance and photo quality :-)

FWIW, S. monadelpha produces smaller scaled leaves (and flowers and fruit) compared to S. psuedocamellia but otherwise looks very similar. Perhaps you have one of each.

Hybrids between those two species sometimes occur among batches of seedlings collected from plantings where both are present. I have seen them among blocks of seed raised stock supplied to retailers here, usually I guess as Stewartia pseudocamellia.

Also there has been a history of the hybrid (S. x henryae) being cultivated mistakenly as S. sinensis in the past.

Closer views of this planting, preferably at flowering time needed for the most reliable responses to be generated here. Individual stewartia plants are identified to the species level using specific bark, leaf, flower and fruit characters.