Need to load from Table 1 to Table 2. Which utility work well here and WHY? - response (3) by ulrich

SQL will be your choice of the same Server.
It will depend on your environment and the szenario if you call it from BTEQ, Teradata Studio or an Python / Java script. The data will not leave the system.
Server to Server - again, what is your setup? Which ETL tool do you use? Big volumes; TPT, Arcmain, Unity data mover (which is using TPT or Arcmain) are the tools of choice. There exists many threads on this in this forum. Check for these.
Very generic question. Without getting specific backgroud you will not get sufficient answers.