Hillary Clinton wasn't making those claims via deranged tweets and speeches from the Oval Office in her position as President of the United States. A private citizen on one hand versus the leader of a country with the power of the press and an angry, violent mob on the other. One person's complaints versus a firehose of misinformation, lies and possibly Russian-backed agitprop being spread by the leader of the country, his party and millions of his followers over four years, culminating in a violent, seditious riot against the very apparatus of democracy and the peaceful transition of power itself. These are not even remotely equivalent in terms of their damage to democracy.
Also, Hillary Clinton wasn't entirely wrong. That there was Russian interference in both the 2016 and 2020 elections on behalf of Trump's campaign is a fact - only the effect of that interference in the first case and the degree of Trump's foreknowledge are in dispute. Meanwhile, there was no actual conspiracy to steal the election from Trump... that was entirely bullshit. Like Hillary Clinton's weird brain disease. And Hillary Clinton's kill count. And Hillary Clinton's pedophile sex slave ring. And all of the Benghazi hearings. And whatever "treason" was supposed to be in the DNC email leaks. And Joe Biden being a pedophile. And Joe Biden having crippling dementia. And whatever Hunter Biden's briefcase was supposed to be about. And whatever the bullshit sandwich du jour for 2024 turns out to be.