While Lucius Malfoy was clearly a powerful individual in the books, his manipulations were fairly clunky, and nowhere near as subtle as portrayed here.

We assume he's competent because Dumbledore keeps referring to him as competent, but Dumbledore does have a motive to exaggerate his enemy's power. He constantly uses Lucius as an excuse to not do something, and he flat out tells Harry early on that weakening Dumbledore strengthens Malfoy.

But Malfoy is in over his head. Every time we see or hear from him, he's getting something wrong, being ineffectual, or being publicly humiliated. By contrast, he seems pretty darn effective in the books. His scheme in Chamber of Secrets was simple and robust enough to work, and even with Harry repeatedly being in the right place at the right time it still ends with the Weasleys discredited and the Malfoys untouched. (Edit: Sorry, misremembered. He goes after Dumbledore prematurely and loses. Good scheme apart from that, though.)

His main obvious difference from canon is the way he's raised his son.