In school they present the Romans as having copied the entire Greek religion. I always thought that seemed like a stupid argument, and remember the sneers of other kids in class. The way i saw it was that Jupiter was identified with Zeus the same way the Jewish Yahweh and the Muslim Allah are regarded as the same god.
On a trip to spain i learned that the Pillars of Hercules were called the Pillars of Melqart by the Phoenicians, who's religion predates the Greek and it appears the Greeks borrowed Hercules from them?
Whats the truth here? Wikipedia suggests Roman mythology has many differences from Greek mythology, and what they share can also be found across the Mediterranean. The Romans even have some of their own gods like Janus and Orcus
It is nearly completely untrue. Your interpretation
The way i saw it was that Jupiter was identified with Zeus the same way the Jewish Yahweh and the Muslim Allah are regarded as the same god.
is a much more correct understanding. The Romans identified their gods with the Greek ones, where there was enough overlap for the identification to be useful; they did the same with other pantheons around Europe, so if you read Caesar's Gallic War you'll see him referring to Gaulish gods by Roman names like Mars and Mercury. We may as well call this practice interpretatio Romana (as it happens the Greeks did the same thing, equating Egyptian and Phoenician gods with their own; there it's called interpretatio graeca).
But it's not totally untrue. Or rather, there are some complications.
The Roman pantheon and Greek pantheon both have a lot of common ground in their origins. There's a very good reason why some of the gods look so similar. Even the names have common origins in some cases: the i̯u- element in Jupiter and the sdeu-, di(w)- of Zeus both come from Proto-Indo-European *diēus, genitive *diu̯os.
In the very early days of Rome, when Greeks first settled southern Italy and Sicily starting in the 800s BCE, there was a lot of cultural contact between the Greeks and the Tyrrhenian natives (especially the Etruscans) which led to a number of Greek mythological figures being adopted by the Italians. In this sense, there was some copying. A number of these elements subsequently got erased from the Roman mythological landscape for various reasons, but some stuck around: the Dioscuri (Castor and Pollux, who were very important in early Roman religion) and Hercules, for example, genuinely were imports.
Once interpretatio Romana took hold, the Romans took the further step of seeing their own gods as involved in Greek mythological stories. Poets, in particular, enthusiastically adopted Greek stories as their own. So, in a sense, this was copying too: but only in the same way that Hollywood "copies" English mythology when making a film about Robin Hood. This has nearly nothing to do with religion as such.