When I bought my first tenor 18 years ago, you had just 3 saxes in the Yamaha range:
Alto= Student model YAS23, Intermediate YAS32, and the top of the range YAS62R.
Same with Tenor apart from the code YTS instead.
I think the 23 didn't have a top F# key and it (and the 32) had clear lacquer instead of the gold lacquer of the 62R.
I was told at purchase that the Yamaha's were copies of the Selmer MKVI's but slightly heavier gauge metal. I tend to agree with this since I've owned both. I never got the sound I wanted from the Yamaha's but prefered the keywork to the newer Selmers.