Need help

I've decided on two Polaris Thermal Weld windows. One installer is offering me
"standard glass (one coat low E)" or "XL glass (two coats low E)".
Another installer would buy the windows from the same place in my city (there is only one that sells Polaris to installers in my city) and only offered me "Energy Smart Supreme Squared Low E". He told me that squared low E is the only way that the Thermal Welds are offered. (?)
I'm totally confused .......are they talking about the same thing? Is standard glass with only one coat low E a single pane window?
Do I really need the Supreme Squared Low E? which I understand would be two coats of low E? I live in central Indiana.
Please don't tell me to question the two installers about this because I've tried. Why would one tell me that squared low E (two coats) is all he can get when they other told me I can get one coat low E? Again, is the latter perhaps referring to a single pane window? Do I really need two coats in Central Indiana? I know I need double panes.

What direction are the windows facing?

Standard Low-e will be adequate in most applications but if you have some summer heat issues, the additional Low-e will be of some help.

No manufacturers are selling single pane windows. All offer double pane with low-e and argon, and some will have two or more versions of that with a single coat of low-e, a double coat, different types of low-e (hard vs soft coat), low-e on different glass surfaces, etc. As a consumer, what you want to look at is not necessarily the details of the type and location of the low-e, but what the thermal performance ratings are, as that tells you how the glass will actually perform and how those details will actually affect you.

In Indiana, you'll want the u-value as low as possible (I like .28 or lower from a double pane), with a moderate shgc of around .27 or higher (it can be lower in a triple pane package).

To proceed, ask both installers what the u-value and shgc of the window that they are proposing is, and also ask for the CPD #, which is the certified products directory on nfrc.org. You can then look the product up and verify those numbers for yourself.

I don't deal with Polaris much, but I'm pretty sure that they offer more than one double pane glass package. That said, there are all different kinds of "dealer agreements", so it is possible that the guy that says he can only get that one package may be telling the truth.
Have you gotten a quote for the UltraWeld? I like it a bit better than the Thermal.