For example in the US they have their elections on a Tuesday (in Australia it is a Saturday), this strikes me as suboptimal if you want the most people to vote then you should hold the election at a time that is convenient for the largest number of people, which is not in the middle of a regular working day.
Australia also has pre-polling (i.e. you can turn up to a polling station and vote before the nominated "election day") and Postal voting (both of which are to my understanding extremely controversial in the US).
I believe in the US you also need to register to vote and you have to take steps to maintain your registration. again that is an added barrier that creates more friction.
Australia also has Preferential voting, I do not believe US elections use this method.