Internation Standards Networking Specification

I seem to get lost when it comes in terms of Networking types and its specifications by different International bodies. I am not able to understand things like -

"synchronous operation on public data networks networking protocol"
"packet mode connected to public data networks by dedicated circuit networking protocol"
"packet switched public data network through a public switched telephone network or an integrated services digital network or a circuit switched public data network networking protocol"
"accessing a Public Data Network from a DTE operating under control of a generalized polling protocol networking protocol"
"International numbering plan for public data networks networking protocol"
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Thanks in advance. Please provide links if any.

Please correct me if I am wrong. The protocols that I have mentioned above are of X-series Recommendations. They talk a lot of "Frame Relay" and "Packet Switched" ... but then they again say that Frame Relay is an example of a packet-switched technology.

Could anyone please let me know the basic differences between "Frame relay" and "packet switched" protocol. When one is preferred over another? Which is more reliable? What is the standard setup for each?