I used sed for a batch ptovess where I could not do it with awk. Vould awk have done it? Or is it more a matter of choice and call awk and sed equivalent for the usage. They both do the common search replace similar with i/o. Is there a good example what can't be done with one that the other can?
One main difference is that an awk program can maintain state and can operate using multiple passes over the same data. A sed invocation is necessarily stateless single-pass because sed (Stream EDitor) is inherently stream-oriented. The advantage, though, is that this makes sed simpler and more appropriate for using in pipe chains.