Are repairable and non-repairable systems modeled in the same way?

No.  For reliability modeling purposes, systems and subsystems are grouped into two categories: repairable or non-reparable.  For repairable systems the measure of interest is often “effective” mean-time-between-failure, sometimes termed mean-time-between-critical-failure (MTBCF). 

For non-repairable systems (e.g., space systems) or systems with some critical mission length, probability of success for a given mission time, is a more common measure.  A description of each type of calculation along with a summary of the most common redundancy equations is described elsewhere in this FAQ.