If you look at the outward practices of Hinduism and Buddhism, they are superficially not the same. The colorful, fantastic gods of Hinduism and their intricate mythology is not what you see in Buddhist temples in Japan, for example. But if you look at Tibetan Buddhism, the colorful and ornate depictions of gods exist there too. They are just differently depicted, differently named, and have different stories behind them.
Because Buddhism and Hinduism are both ancient religions, a lot of artistic imagery has developed to aid worshippers on their path. Sometimes this deviates away from the simple principles of the mystical basis of both of these religions and becomes idolatry. But that is what religion does. It physical-izes things so non-mystics can enjoy the religious experience too.
Buddha was a monk who owned nothing, Yogis own nothing, yet huge structures of worship have been built around what they teach. These structures are richly decorated. They provide the opportunity for supplicants to ask the gods for what they want in life. This is contrary to what all the great mystics taught, including Buddha, when he said, “Be a Light to Yourself.”