People often think that Jupiter, King of the Roman Gods, and Zeus, King of the Greek Gods, are the same god.
But the truth is that Jupiter was as different from Zeus as the ancient Romans were from the ancient Greeks.
The Romans worshiped thousands of gods. As they expanded their empire, they discovered new gods from the people they conquered. When they ran into a god (or goddess) they liked, they adopted him (or her.) When they heard about the Greek gods, they adopted nearly all of them.
They gave the Greek gods Roman names, and acted as if they had been Roman gods all along.
But they did more than that. The ancient Romans changed some of the Greek myths to better reflect Roman beliefs. They changed some of the Greek gods' personalities to better reflect the Roman way of life. This did not happen overnight.
In Roman mythology, for example, Jupiter rarely, if ever, came down to earth. He ruled from the heavens above, and his word was final. (The Greek God Zeus, on the other hand, was forever showing up on earth in disguise, and had a great time doing it. He was terrified of his wife Hera, and somewhat ruled himself by the Fates.)
Juno, the Queen of all the Roman Gods, was motherly. Her job was to watch over the women of Rome. When she wasn't doing that, she was busy with her own children and her own household. (Hera, the Queen of all the Greek gods, was jealous and petty. When she wasn't keeping an eagle eye on Zeus, she was plotting against any god or mortal who had angered her.)
The truth about myths is that they change with the storyteller, the civilization, the times, and the translation.
Still, the Greek myths were so wonderful that the ancient Roman storytellers and poets and writers might change some them, to bring them closer to the Roman way of life, but overall, they left quite a few of them very close to the way they found them, and treated the ancient Greek myths as great stories, which indeed they are!