That is precisely my understanding.

The Garden is a very small little lounge for EVA's top end elites. High end food and beverage, but no showers. EVA Diamond only.

The Infinity and the Star are equivalent in size and with similar food and beverage (as compared to each other). Both have shower facilities. The former is for business class fliers and the latter is for *G in Y. Not sure where EVA puts their own Gold's flying in Y. The only difference is the aesthetic themes and the fact that Star feels a little more crowded than Infinity.

I'm not an expert. I've only been in each lounge once. and I don't speak mandarin. but this is my understanding.