Both device contains same number (1508) of Pin Count for FineLine BGA package. It's just both are different device type.
EP2S'90'F'1508'I4 and EP2S'180'F'1508'I4
Check the difference in below link (Figure 6–1. Stratix II Device Packaging Ordering Information) - Page 248
For more info, check the below link for difference according to DigiKey.