In English they mean the same: regard as;consider;look upon as。
But they're different.
看做:The solar halo is often regarded as the weather change the omen. 日晕常被看做天气变化的预兆。
看作:Dies regards as to go home to be the same likely. (Described that does not fear death )〔视死如归〕把死看作像回家一样。形容不怕死。