There's not too much difference; Make sure you do the install from the Active node, the install wizard will detect that you have a clustered instance (or instances) and will prompt you to select the instance(s) to be patched. The install process will patch BOTH nodes (assuming a 2-node cluster) so you only need to do it once.

You'll need to reboot each node after the install.

The readme files for each Service Pack usually contain a section with specific instructions or points to note when installing on a Failover Clustered Instance.

Lempster