If you're getting wildly different plans between servers, there has to be differences. The differences can be in the statistics on the data in the database. The differences can be in the data. The differences can be in the structures. The differences can be in the database settings. The differences can be in the server settings.

Follow Gianluca's advice to identify differences in the server settings and database settings. After that, determining why there are differences just looking at or comparing plans requires stepping out of the plans and looking at the rest of the structures, data & statistics. However, the plans should point you in the right direction to start the comparison.