Two temples in Yogyakarta. Mendut Temple has 2 tickets and tours to book; Prambanan Temple has 297 tickets and tours to book. The table and the two notes below put them side by side; the full pages have what to see, the ticket and the timing for each.
Mendut has its own small ticket office and the entry fee is modest, paid on the day; it is not covered by the Borobudur ticket, and there is nothing to reserve ahead. Most visitors arrive by car from Yogyakarta, about 40 km to the south-east, or stop on the way back from Borobudur, which lies 3 km to the west.
Online, Mendut appears only as part of wider day trips. The most common is a full day from Yogyakarta that covers Borobudur, the small temple of Pawon and Mendut in the morning and then drives east to the Hindu temples of Prambanan for the afternoon, with a driver, an air-conditioned car and sometimes a guide included;
Prambanan is easy to visit independently: you buy an entry ticket at the gate or online, and the ticket covers the main compound and the walk north to the Buddhist temples of Lumbung, Bubrah and Sewu within the same archaeological park. Combination tickets with Borobudur, or with the Ratu Boko hilltop site nearby, are sold as well and save a little on separate entry.
Most of what is booked online combines Prambanan with something else. The classic day trip from Yogyakarta covers Borobudur in the morning and Prambanan in the afternoon, sometimes with a sunrise viewpoint, the Merapi volcano by jeep or the small temples of Plaosan and Ijo added on.