| A failure can be defined as an unexpected event within a service that prevents it from functioning normally. When a failure occurs, it can generally prevent responses to the current and possibly all following client requests. | Errors are different from failures. An error is a common condition that can appear during input validation that will be communicated to the client as part of the message's normal processing. |
| Failures are unexpected, and they require intervention before the system can resume at the same level of operation as earlier. | Errors are an expected part of normal operations. We can deal with errors immediately, and the system will continue to operate at the same capacity following an error. |
| It does not mean that failures are always fatal. Rather, some capacity of the system will be reduced following a failure. | Errors are not fatal. They are part of the programming and can be occurred anytime. |