Farm Level Solutions -
Farm-level solutions are scoped at the SharePoint farm level, so they have full-trust access to all the resources and functionality in SharePoint.
Application build using Farm level –
All SharePoint applictaions can be deployed with Farm level scope.
Sandboxed Solutions –
Sandboxed Solutions are solutions that run in the context of a site collection. Sandboxed solutions are restricted.
Application build using Sandboxed Solutions –
They cannot connect to resources that are not on the local server, access a database, call unmanaged code, write to the system disk, or access resources in a different site collection. Sandboxed solutions, though,do have the capability to monitor and shut down applications, should they have any performance issues.