Perun (Cyrillic: Перýн) is the highest god of the pantheon and the god of sky, thunder, lightning, storms, rain, law, war, fertility and oak trees. His other attributes were fire, mountains, wind, iris, eagle, firmament (in Indo-European languages, this was joined with the notion of the sky of stone, horses and carts, weapons (hammer, axe (Axe of Perun), and arrow), and war. He was first associated with weapons made of stone and later with those of metal.
In Slavic mythology, much like in Norse and Baltic mythologies, the world was represented by a sacred tree, usually an oak, whose branches and trunk represented the living world of heavens and mortals, whilst its roots represented the underworld, i.e. the realm of the dead. Perun was the ruler of the living world, sky and earth, and was often symbolised by an eagle sitting on the top of the tallest branch of the sacred tree, from which he kept watch over the entire world. Deep down in the roots of the tree was the place of his opponent, symbolised by a serpent or a dragon: this was Veles, watery god of the underworld, who continually provoked Perun by creeping up from the wet below up into the high and dry domain of Perun, stealing his cattle, children, or wife. Perun pursued Veles around the earth, attacking him with his lightning bolts from the sky. Veles fled from him by transforming himself into various animals, or hiding behind trees, houses, or people; wherever a lightning bolt struck, it was believed that this was because Veles hid from Perun under or behind that particular place. In the end, Perun managed to kill Veles, or to chase him back down into his watery underworld. The supreme god thus reestablished order in the world, which had been disrupted by his chaotic enemy. He then returned to the top of the World tree and proudly informed his opponent down in the roots "Well, there is your place, remain there!" (Ну, там тваё мейсца, там сабе будзь!). This line came from a Belarusian folk tale. To the Slavs, the mythological symbolism of a supreme heavenly god who battles with his underworldly enemy through storms and thunder was extremely significant.
While the exact pantheon characterization differed between the various Slavic tribes, Perun is generally believed to have been considered as the supreme god by the majority, or perhaps by nearly all Slavs, at least towards the end of Slavic paganism. The earliest supreme god was probably Rod; it is unclear precisely how and why his worship as the head of the pantheon evolved into the worship of Perun. Another candidate for supreme deity among at least some Slavs is Svarog.
Jupiter (Latin: Iūpiter [ˈjuːpɪtɛr] or Iuppiter [ˈjʊpːɪtɛr], from Proto-Italic *djous "day, sky" + *patēr "father", thus "sky father"), also known as Jove (gen. Iovis [ˈjɔwɪs]), is the god of the sky and thunder and king of the gods in ancient Roman religion and mythology. Jupiter was the chief deity of Roman state religion throughout the Republican and Imperial eras, until Christianity became the dominant religion of the Empire. In Roman mythology, he negotiates with Numa Pompilius, the second king of Rome, to establish principles of Roman religion such as offering, or sacrifice.
Jupiter is usually thought to have originated as a sky god. His identifying implement is the thunderbolt and his primary sacred animal is the eagle, which held precedence over other birds in the taking of auspices and became one of the most common symbols of the Roman army (see Aquila). The two emblems were often combined to represent the god in the form of an eagle holding in its claws a thunderbolt, frequently seen on Greek and Roman coins. As the sky-god, he was a divine witness to oaths, the sacred trust on which justice and good government depend. Many of his functions were focused on the Capitoline Hill, where the citadel was located. In the Capitoline Triad, he was the central guardian of the state with Juno and Minerva. His sacred tree was the oak.
The Romans regarded Jupiter as the equivalent of the Greek Zeus, and in Latin literature and Roman art, the myths and iconography of Zeus are adapted under the name Iuppiter. In the Greek-influenced tradition, Jupiter was the brother of Neptune and Dīs Pater, the Roman equivalents of Poseidon and Hades respectively. Each presided over one of the three realms of the universe: sky, the waters, and the underworld. The Italic Diespiter was also a sky god who manifested himself in the daylight, usually identified with Jupiter. Tinia is usually regarded as his Etruscan counterpart.