When and how did the Greek mythos transfer to the Romans?
It seems that there are a great many similarities between Roman and Greek Mythology. In fact, many people consider them synonymous and only really differ in the names. For example:
* Greek ⇄ Roman
* Zeus ⇄ Jupiter
* Poseidon ⇄ Neptune
* Hades ⇄ Pluto
* Hermes ⇄ Mercury
And many others.
My impression is that they are nearly identical, so I want to know when, why and how did the Roman people adopt the Greek Mythos? Did they bring it with them? Is there evidence that they believed something else first that evolved into a Greek-like mythos?
If this belief is false, please point out where the Roman mythology differs from the Greek and why that is significant enough to say they are different religions.