The Scientific world uses complete names to reference species within families so while it looks like you could simply use the letter of the family/ species name and it would only refer to that specific item, it simply isn't so. We use the family name first then the species name, this can lead to a lot of different types of organisms looking like they are related when they really aren't. Using your question as the example. C. sinensis may refer to: Camellia sinensis,, a plant species whose leaves and leaf buds are used to produce tea Celtis sinensis, the Chinese hackberry, a flowering plant species native to slopes in East Asia Centropus sinensis, the greater coucal or the crow pheasant, a bird species widespread in Asia, from India, east to south China and Indonesia Cephalotaxus sinensis a coniferous shub or small tree species native to central and southern China Citrus sinensis, the sweet orange Clonorchis sinensis, a human liver fluke species Cryptolepis sinensis, a plant species Cordyceps sinensis, a species of fungus Calyptraea sinensis, a synonym for Calyptraea chinensis, a sea snail species So the answer is No, not all things refered to as C. sinensis are tea.
My bad, was very tired when I wrote that. Yes Camellia sinesis variations is what I was referring to since there are so many variations. For example, under the Camellia sinensis, refers to 7 cultivars, but apparently I have #8, var. Louisiana. Thus I am wondering if all Camellia sinesis are tea plants.
In a purely unscientific way the one I bought for tea had the small leaves and doesnt mind full sun(was labelled as tea) the other Camellia has large leaves and prefers shade. Heres a guy who made tea from the regular flowering camellia https://pandragonathome.blogspot.com.au/2009/11/making-black-tea-from-your-camellia.html