Default: This is the default file installed with the ReadingPlan app. It differs from the usual version in that the last three books in the fourth reading are Luke, John and Psalms, rather than Psalms, Luke and John.
Original: This appears to be the original plan. It differs from the plan installed by default in the order of books in the fourth reading, see above.
Readings 1, 2, and 3: This plan omits the fourth reading from the original plan, so that the New Testament and Psalms are read just once in a year instead of twice. (Order is Gospels, Psalms, Acts, Epistles.)
Readings 1, 3 and 4: This plan omits the second reading from the original plan, so that the New Testament and Psalms are read just once in a year instead of twice. (Order is Acts, Epistles, Matthew, Mark, Psalms, Luke, John.)
2-Year Plan: This is Don Carson's edition of M'Cheyne's calendar, from Ben Edgington's web site. The readings are spread over two years, taking you through the New Testament and Psalms once every year, and the Old Testament once every two years.