In terms of initial purchase costs, hydraulic systems and system components are associated with hefty price tags. While pneumatic systems and system components may not carry such a high initial purchase cost, they are linked with rather high operating costs.
When hydraulic system components fail, it can create quite a mess since hydraulic systems use a lot of oils or other liquids. Pneumatic system component failure may not result in a mess because pneumatic systems are air powered. However, sometimes gases are used in pneumatic systems, which may be toxic if inhaled.
According to Science Ray, hydraulic systems have the capability of being able to operate under much higher pressures than pneumatics. However, hydraulic systems are much more complex, requiring operators with more skill and training to perform repairs and regular maintenance.