It's important to mention that there are two different types of "Maoism": Mao Zedong Thought, which was the ideology of the Communist Party of China and stems from Soviet Marxism-Leninism, and Marxism-Leninism-Maoism, which was never in power in China, though numerous groups across the world (most notably the Filipino New People's Army, the Indian Naxalites, the Nepalese Maoists who won the civil war a decade ago, and the Shining Path in Peru) claim it as their ideology. The difference between the two is that the former bolts on select additions of Mao's contributions to Marxism-Leninism, while the latter holds that Mao was significant enough to warrant being an entire new stage of Marxism entirely.

Now, on to your question: Mao and much of the CPC considered the Soviet Union thoroughly revisionist and corrupt during the post-Stalin years, which, from a Marxist standpoint, they certainly were. Hoxha backed Mao on this decision, and they both cut ties with Moscow due to this. However, as time went on, and Mao began to make what Marxists would call "right-opportunist" (i.e. aligning with the enemies of socialism against fellow socialists for the sake of "purity") errors, most notably opening relations with Nixon and fighting several small-scale wars with the Soviet Union and her allies, Hoxha broke with Mao, considering this, too, to be revisionism. Hoxha's branch of Marxism is often called "anti-revisionism" for these reasons.

Many Marxist-Leninists (MLs) today, though upholding the USSR, China, and Albania as socialist, follow Mao Zedong Thought and uphold his criticisms of Soviet revisionism, though also critique Mao's own revisionism; Marxist-Leninist-Maoists (MLMs) don't believe Mao made any errors at all; and Hoxhaists/Anti-Revisionists consider both the Soviet Union and China to have been indefensible.