https://www.ustires.org/whats-tire-0

https://www.continental-tires.com/car/tire-...cs/tire-mixture

https://en.wikipedia.org/wiki/Tire

Everything just a google search can get a lot information nowadays.. 

Just to add so that it answers your question directly:

The number indicates how much of that material is present. There are two places where this is checked and labelled:
1. The tread counts the number of material if you cut through the tire directly in the middle
2. The sidewall counts the number of material as you cut through the sidewall

So for example:
Tread: 1 polyester + 2 steel + 2 nylon
Sidewall 2 polyester
This means that there is 1 polyester body ply at the middle of the tire followed by 2 layers of steel belts and finally 2 layers of nylon cap material that is present at the center of the tire (from bottom to top)

At the sidewall there is 2 layers of body ply material. In this case it is the same ply material that is found at the center but wrapped around by the bead and runs up the sidewall.

Different tires will have different combination of body ply, and nylon cap depending on its speed rating and required performances. All car tires will have 2 layers of steel belts.

Yes I wouldn't expect them to publish because even if the same tire size e.g. 185/55R15 under the same company - the tire construction will vary depending on again the speed symbol of the tire and the performances required. The best combination is actually the one that is on the actual tire as that combination has been tested and will meet all the regulatory and safety requirements set by the company and by the law.

It is not possible to say which is better just by comparing the number of polyester/steel/nylon written on the tire. So please don't try to look into these numbers too much. They are there mainly for legal purposes.

And just to give you an idea as to why it is not possible - There a multiple variations of polyester body ply that is used in a tire by a single manufacturer and each manufacturer uses their own variation. So even if you have two tires stating that they have 1 polyester body ply like your example, I cannot tell you which is better because i do not know what type of polyester are the using. The same goes for the steel belt material and the nylon cap.