When I look at the trusted certificates in my browser, I see that many certificate authorities have multiple root certificates associated with them. For example,
Amazon Root CA 1,
Amazon Root CA 2,
Amazon Root CA 3, and
Amazon Root CA 4.
How do the purposes of these four certificates differ?
I also see that some CAs have root certificates of different "tiers", such as
platinum. What's the deal with these? I imagine there are price differences associated with the different tiers, but what extra service could they be offering?