The answers in this section on autocephaly were provided by a seminary faculty member in a 1970 OCA publication.
What is the difference between an “autocephalous” and an “autonomous” church if both types are truly independent?
An “autocephalous” Church is completely self-governing. It elects its own primate and has the right to consecrate its own Holy Chrism, among other prerogatives unique to autocephalous Churches. [The term “autocephalous” literally means “self-heading.”]
An “autonomous” Church is self-governing to a certain degree in its internal matters, but its head is appointed or confirmed by the autocephalous Church which nurtures it. An autonomous Church also receives its Holy Chrism from its “Mother Church.”
The Orthodox Church in America is an Autocephalous Church, having received its Tomos of Autocephaly from the Russian Orthodox Church in 1970.