SSL certificates. Help to find a path in the dense forest

Hey.
Faced the problem of choosing an SSL certificate for your project. The topic turned out to be so extensive for me that I just don’t know which way to approach its solution and therefore I would like to ask knowledgeable habraktraktik to chew on me and colleagues on the habr-shop (with similar interest) about all the intricacies of SSL certificates.

“What is really with them?”
“Why is the difference in cost so big? What does it depend on? ”
“Should I rely solely on price, or are there serious technical aspects?”
“If I switch from one hosting provider to another, will the certificate expire?”

For example, my hoster offers several to choose from (price per year):

GeoTrust QuickSSL Premium Certificate - 5000 rubles
RapidSSL Certificate - 800 rubles
RapidSSL Wildcard Certificate - 8000 rubles
Thawte SSL123 Certificate - 3000 rubles
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what for example and why?

Thank you in advance for your understanding and assistance.