I'll assume you know how to use their website.
The primary difference is that any "extended protection" oil must have higher oxidation resistance since oxidation is typically what ends an oil's service life.
"High mileage" just means seal conditioners are added.
FWIW, there is no product called "maxlife synthetic."-- there is this though:
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So if you are asking about primarily what makes an oil "extended protection" or not, it's basically the oxidative stability (and cost) of the base oils.