Two temples in Yogyakarta. Borobudur has 370 tickets and tours to book; Ijo Temple (Candi Ijo) has 6 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.
Visiting Borobudur now involves two decisions rather than one. A standard ticket admits you to the temple park, where you can walk around the base of the monument and its gardens. Climbing onto the monument itself requires a separate, quota-limited ticket that is sold in timed slots and includes a local guide and the woven sandals that all climbers must wear to protect the stone. Numbers on the structure are capped each day, so the climb sells out at busy times, and buying it in advance or through a tour that guarantees it is worthwhile.
Most visitors come from Yogyakarta, about 40 km away, and the tours reflect that.
Candi Ijo does not sell its own tickets online. Entry is paid at a small booth by the car park, the fee is modest, and there are no timed slots or queues to beat. What you are really choosing is how to get up the hill, because the temple sits on a slope about 18 km east of Yogyakarta and public transport does not reach it in any useful way.
The most popular option is a late-afternoon tour that ends at Ijo for sunset. These usually start with one or two of the big monuments, typically Prambanan, Plaosan or even Borobudur in the morning, and finish on the hill as the light drops over the plain.