What is the difference between Process Capability and Process Performance

Process Capability describes the $$capability$$ or the best, a process could currently be expected to produce. It address how well a process is executing relative to customer specifications over a short term operation

Process Performance describes how well a process meets customer specifications. It address how well a process is executing relative to customer specifications over a long term operation

Process Performance is calculated using the sample standard deviation associated with the data samples where$-$as Process Capability is calculated using an estimated standard deviation that is equal to Rbar $($average range$)$ divided by d$2($SPC constant$)$