How different are the rules for registration and voting in different states, (specifically the rules on early voting and the rules on access to polling places during voting), and how do those practices differ from the norms in other advanced democracies?
Background of this question:
After a wave of new rules being passed by (mostly) Republican state legislatures, and an attempt by Congress to pass the For The People act, there is much debate over reforming the US election rules; specifically about how to register to vote, and how to vote.
Democrats believe the 2021 Republican rules are voter suppression; Republicans argue that many Democrat-leaning states already have tighter rules (e.g. this paywalled Wall Street Journal op-ed by Karl Rove).
As a non-American, the state of US election rules looks like an inconsistent mess. My previous question on this topic was too opinionated, so I'm asking this question in an attempt to put the general state of US election rules in a factual context.