The difference comes from the number of stars shown on each of the three night sky poster sizes.
The A2 is twice as big as the A3 star map, and the A3 is twice as big as the A4. Due to A3 and A4 being smaller, it's harder to show the smaller stars on them. Therefore, the A2 - Large star map will have the highest accuracy with most stars shown as compared to Medium and Small posters.
All posters are printed on same quality paper using the same printers and going through the same strict quality assurance process! Go to our Star Map Builder to find the right poster size for you!